Revisiting The Numbers Racket

 

 

 

# 6739

 

An excellent piece by Kelly Crowe of CBC News over the weekend questions the credibility of flu mortality numbers and reminds us, once again, that in public health easy answers are often the hardest to deliver.

 

First a link to the article, which I encourage you to read in its entirety. 

 

Flu deaths reality check

Credibility of flu models disputed

By Kelly Crowe, CBC News

Posted: Nov 25, 2012 5:14 PM ET

Do thousands of Canadians really die every year from the flu? The flu folks keep saying so. I've already heard it repeated several times this year and flu season has just started. This is what the Public Health Agency of Canada said in a recent press release: "Every year, between 2,000 and 8,000 Canadians die of the flu and its complications."

(Continue . . . )

 

 

Long time visitors to this blog will recall that we’ve trod this perilous path before - for both seasonal and pandemic flu - along with a variety of other diseases.  

 

Quite understandably, the public and the media expect public health officials to have some kind of handle on the number of deaths caused by infectious diseases in our society. 

 

Particularly with something as ubiquitous as flu.

 

But the truth is, no one really knows.

 

After more than a decade of promoting the `flu kills roughly 36,000 Americans each year’ meme, the CDC revised (and hopefully improved) their estimates in 2010 ( see MMWR: Estimates Of Yearly Seasonal Influenza Deaths)

 

For deaths with underlying pneumonia and influenza causes (the most narrow definition of flu-related fatalities used) the models estimated a yearly average of 6,309 (range: 961 in 1986--87 to 14,715 in 2003--04) influenza-associated deaths.

 

Using a broader criteria (underlying respiratory and circulatory causes including pneumonia and influenza causes)  the models estimated an annual average of 23,607 (range: 3,349 in 1986--87 to 48,614 in 2003--04) influenza-associated deaths.

 

Despite the 12-fold difference in deaths between the 1986-87 and 2003-04 seasons, the operative word here remains `estimated’. 

 

• Estimates are extrapolated based on a surveillance subset of the country, not the whole nation
• There are often co-circulating viruses that may influence overall mortality.
• Surveillance, testing, and reporting may change over time
• Different mathematical models can produce differing results
• There are varying opinions as to what constitutes an influenza-related fatality.

 

When combined with the inevitable variations in the severity of influenza seasons (H3 years are usually more severe than H1 years), this makes it impossible to derive a single number that `works’.

 

In an attempt not to compound a felony, I try to leave it as influenza `kills thousands each year’ or `is the cause of substantial mortality’ in this blog. Sometimes I’ll use the range (3,000-48,000) offered by the CDC, but most of the time I don’t.

 

The same holds true for just about any illness or disease you’d care to mention. 

 

Ask the CDC how many people contracted West Nile Fever this summer, and they will tell you that (as of Nov. 20th) they had recorded  5,207 cases of West Nile virus disease in people, including 234 deaths, but that the real number may be 50 times higher.

Severe (neuroinvasive) cases are pretty easy to spot, but they estimate only 1%-3% of mild cases of West Nile Fever are diagnosed and reported.

 

If we do the math, and assume the 2654 non-neuroinvasive cases officially reported constitute between 1% and 3% of the total number of actual cases we get a range of between 250,000 and 85,000 infections.

 

The chart below illustrates the problem nicely. 

 

 

Relying only on lab confirmed fatalities isn’t much of a solution, either. The `official’ death toll for the 2009 pandemic - as reported by the World Health Organization  - was roughly 18,000 deaths globally.

 

The WHO offered this disclaimer:

 

The reported number of fatal cases is an under representation of the actual numbers as many deaths are never tested or recognized as influenza related. – World Health Organization.

 

Unfortunately, the mainstream media often reported the low official number of deaths without adequately explaining the acknowledged gaps in the data, leading many to believe that the 2009 pandemic was a damp squib.

 

In contrast, earlier this year, in Lancet: Estimating Global 2009 Pandemic Mortality, we saw a study who’s estimate found:

 

We estimate that globally there were 201 200 respiratory deaths (range 105 700—395 600) with an additional 83 300 cardiovascular deaths (46 000—179 900) associated with 2009 pandemic influenza A H1N1. 80% of the respiratory and cardiovascular deaths were in people younger than 65 years and 59% occurred in southeast Asia and Africa.

 

 

With no way to accurately count cases, analysts are reduced to creating mathematical models, fueled by both hard data and assumptions, in order to extrapolate the impact of diseases on the population.

 

The old adage (well, not that old, as it is attributed to George E. P. Box, Professor Emeritus of Statistics at the University of Wisconsin) is that:

 

“All models are wrong, but some models are useful.”

 

To that I would add, that while useful, mathematical models can be extraordinarily difficult to defend.

 

It requires agreement over assumptions.  And among academics, that’s never easy to reach.

 

Going hand-in-hand with the estimates of flu deaths each year has been the purported effectiveness of the seasonal flu shot.

 

Up until about a year ago the CDC’s mantra has been for healthy adults under the age of 65, in years when the vaccine is a good match to circulating strains, effectiveness ranges from 70%-90%.

 

Despite these important qualifiers, the message often ended up being shortened in the media to the flu vaccine being `up to 90% effective’.

 

A little more than a year ago the CDC updated their FAQ on Flu Vaccine effectiveness, and as part of a much longer detailed posting, lowered their estimate of the inactivated flu shot’s effectiveness to read:

 

. . . recent RCTs of inactivated influenza vaccine among adults under 65 years of age have estimated 50-70% vaccine efficacy during seasons in which the vaccines' influenza A components were well matched to circulating influenza A viruses.

 

A number that pretty much matched CIDRAP’s finding (see A Comprehensive Flu Vaccine Effectiveness Meta-Analysis) which would be released a couple of weeks later. That analysis showed the trivalent inactivated vaccine (TIV) had a combined efficacy of 59% among healthy adults (aged 18–65 years).

 

So what are we left with?

 

Well, every time we get into statistics (admittedly not my strong suit) I’m reminded of the story of the statistician who drowned trying to ford a river that was, on average, only 3 feet deep.

 

Still I think we can safely draw a few conclusions.

 

Influenza-like-Illnesses (ILIs) obviously contribute to a good deal of morbidity and mortality each year. 

 

In addition to influenza, these illnesses can be caused by the metapneumovirus, parainfluenzavirus, respiratory syncytial virus (RSV), adenoviruses, or any of the myriad Rhinoviruses (Common cold).  Among others.

 

The percentage of these illnesses that are actually due to the influenza virus varies considerably from year to year, and so only a portion of these deaths are actually `vaccine preventable’.

 

Today’s influenza vaccine, whose effectiveness is described as just `moderate’ by CIDRAP’s recent 160-page Comprehensive Influenza Vaccine Initiative (CCIVI) report, undoubtedly saves lives and reduces hospitalization, but is not the panacea that many would hope for.

 

 

Hence the call for better vaccines.  

 

Despite their limitations, I still get a flu vaccine each year, as I believe partial protection beats no protection any day of the week.

 

As far as the estimate of deaths from influenza are concerned, I doubt this debate can really be solved to everyone’s satisfaction. There is no single, `good’ answer when the parameters change as often as they do with influenza.

 

We live in a world driven by easily adopted memes, 10 second sound bytes, and 140 character tweets.

 

As a result, officials are often tempted to provide us with simplified, easy to digest, answers. While brevity may have many advantages, scientific precision is rarely one of them. 

 

Of course, if someone comes up with a better way to measure the number of deaths from influenza each year, I’ll feature it in this blog.  Until that happens, I’ll simply leave it as the cause of `substantial mortality’.

»» Read More

IDSA: Pandemic and Seasonal Influenza Preparedness

 

 

# 6556

 

This morning the IDSA (Infectious Disease Society of America) and the AMA held a 2-hour webinar as part of the launch of an updated set of IDSA guidelines designed to educate federal policymakers on the issues of Pandemic and Seasonal Flu preparedness.

 

You’ll find a summary of their recommendations, and the link to download the 24-page PDF file at IDSA webpage below:

 

 

Pandemic and Seasonal Influenza

 

IDSA has published (September 2012) an updated set of Pandemic and Seasonal Influenza Principles for United States Action to educate federal policymakers about how best to prepare for and respond to seasonal and pandemic influenza.

 

IDSA's first set of principles was issued in 2007 (see previous version here).  IDSA's updated principles rely upon the experience of the 2009 H1N1 influenza pandemic and are intended to assist the U.S. Department of Health and Human Services' (HHS) Assistant Secretary for Preparedness and Response (ASPR) and other agency officials as they establish priorities for implementation of the reauthorized Pandemic and All-Hazards Preparedness Act (PAHPA).

What Action Does IDSA Recommend?

IDSA strongly believes that much work remains ahead of us, and overall responses to seasonal influenza and pandemic preparedness must be closely interrelated. The Society calls for:

• coordination between HHS and other U.S. government departments, as well as a need for better coordination within HHS, particularly concerning influenza vaccine efforts
• establishing processes for continual review of critical and rapidly evolving components of influenza preparedness, such as the contents of the Strategic National Stockpile (SNS)
• vigorously supporting the uptake of the annual influenza vaccine by health care workers including through the adoption of a mandatory approach (see IDSA's revised policy statement (PDF) for details)
• significant and sustainable multi-year funding that may be used flexibly particularly by local health departments for "All-Hazards" preparedness

 

(Continue . . . )

 

While many items were discussed during today’s webinar, the take-away message is that while much progress has been made in recent years, the United States remains vulnerable to many pandemic and other biological threats.

Influenza is by far the best known threat, but isn’t the only pandemic possibility.

 

The IDSA Guideline, in its conclusion, sums it up this way:

 

Influenza remains among the greatest infectious disease threats to our nation and the global community.  Despite the investments and progress made in research and preparedness over the past decade, substantial gaps remain. The next influenza pandemic is inevitable, only the timing,  severity,  and point of origin remain unknown.  We cannot be complacent. We cannot afford to be penny-wise and pound-foolish,  eroding the  progress made and leaving our nation and the world vulnerable.  We must be prepared.

»» Read More

EID Journal: Revisiting The `Canadian Problem’

 

Photo Credit PHIL

# 6267

 

 

In September of 2009, just as the second wave of the H1N1 pandemic was ramping up, news of an unpublished study began to surface in Canada that suggested that those who had received a seasonal flu shot the previous year were more susceptible to the new pandemic virus than those who hadn’t.

 

Helen Branswell, science and medical reporter for the Canadian Press, was among the first to report on it (see Branswell On The Canadian Flu Shot Controversy).

 

 

This bombshell – which began to be known as `the Canadian problem’, sent shockwaves through public health agencies, many of whom were just days away from starting up their seasonal flu vaccination campaigns as they waited for the arrival of the H1N1 pandemic vaccine expected later in the fall.

 

Suddenly, there was genuine concern that with a pandemic virus on the way, that rolling out the seasonal vaccine might be the wrong thing to do.

 

The CDC and the World Health Organization both scrambled to look at their available data, and stated that they could find no correlation between the seasonal vaccine and susceptibility to the pandemic flu . . . but that they would continue to look.

 

Meanwhile, with concerns rising, a number of Canadian Provinces halted or announced delays in their seasonal flu shot campaign, even though the study had yet to be published (see Ontario Adjusts Vaccination Plan).

 

October saw a number of new reports and studies that failed to corroborate the (still unpublished) findings, including a study published in the BMJ (British Medical Journal) that suggested exactly the opposite - that getting the seasonal flu vaccination may be slightly protective against the swine flu  (see When Studies Collide).

 

By November, with no compelling corroboration of the `Canadian Problem’, Canada’s National Advisory Committee on Immunization (NACI) came out in favor of resuming seasonal flu jabs (see NACI: Canada Should Resume Seasonal Flu Vaccinations).

 

The controversy wasn’t over, however.

 

In April of 2010 these Canadian studies were finally published by PLoS Medicine. Writing for CIDRAP, Maryn McKenna   detailed their findings.

 

New Canadian studies suggest seasonal flu shot increased H1N1 risk

Maryn McKenna Contributing Writer

Apr 6, 2010 (CIDRAP News) – Despite a rapidly launched range of studies, investigators in Canada are still unable to say—or to rule out—whether receiving a seasonal flu vaccination in the 2008-09 season made it more likely that Canadians would become ill from 2009 pandemic H1N1 flu.

(Continue . . .)

 

Other studies, however, failed to show any correlation, leaving us with a bit of a mystery on our hands. 

 

Fast forward to today and we’ve another study that appears ahead of print in May’s edition of the CDC’s EID Journal that looks at this supposed link, and once again, finds no evidence to support it.

 

 

Volume 18, Number 5—May 2012

Research

No Association between 2008–09 Influenza Vaccine and Influenza A(H1N1)pdm09 Virus Infection, Manitoba, Canada, 2009

Salaheddin M. Mahmud , Paul Van Caeseele, Gregory Hammond, Carol Kurbis, Tim Hilderman, and Lawrence Elliott

Abstract

We conducted a population-based study in Manitoba, Canada, to investigate whether use of inactivated trivalent influenza vaccine (TIV) during the 2008–09 influenza season was associated with subsequent infection with influenza A(H1N1)pdm09 virus during the first wave of the 2009 pandemic.

 

Data were obtained from a provincewide population-based immunization registry and laboratory-based influenza surveillance system.

 

The test-negative case–control study included 831 case-patients with confirmed influenza A(H1N1)pdm09 virus infection and 2,479 controls, participants with test results negative for influenza A and B viruses. For the association of TIV receipt with influenza A(H1N1)pdm09 virus infection, the fully adjusted odds ratio was 1.0 (95% CI 0.7–1.4). Among case-patients, receipt of 2008–09 TIV was associated with a statistically nonsignificant 49% reduction in risk for hospitalization.

 

In agreement with study findings outside Canada, our study in Manitoba indicates that the 2008–09 TIV neither increased nor decreased the risk for infection with influenza A(H1N1)pdm09 virus.

 

 

While the bulk of studies have shown no causal link between receipt of the seasonal vaccine and contracting the 2009 H1N1 virus, the results have not been 100% in alignment.

 

Leaving us with a bit of a mystery.  Why should some Canadian studies differ from those done elsewhere?

 

One fascinating hypothesis that might explain these disparate findings was proffered back in 2010 in the journal Eurosurveillance.

 

The authors suggested that infection by any influenza (or perhaps, any I-L-I) ramps up the body’s immune system for a time, making that person temporarily less susceptible to infection by another respiratory virus.

 

Since the pandemic arrived on the heels of the flu season in the northern hemisphere, those who received flu shot in the fall and thereby avoided illness might have been more likely to catch the pandemic strain than someone who had endured a bout of flu (and thereby acquired temporary generic immunity) over the winter.

 

You’ll want to read the entire paper, but I’ve included excerpts (reparagraphed for readability) from the abstract below.

 

 

Eurosurveillance, Volume 15, Issue 47, 25 November 2010

Perspectives

Seasonal influenza vaccination and the risk of infection with pandemic influenza: a possible illustration of non-specific temporary immunity following infection

H Kelly , S Barry, K Laurie, G Mercer

ABSTRACT (Excerpts)

We found no evidence that seasonal influenza vaccine increased the risk of, or provided protection against, infection with the pandemic virus.

 

Ferret experiments have suggested protection against pandemic influenza A(H1N1) 2009 from multiple prior seasonal influenza infections but not from prior seasonal vaccination.Modelling studies suggest that influenza infection leads to heterosubtypic temporary immunity which is initially almost complete.

 

We suggest these observations together can explain the apparent discrepant findings in Canada and Victoria. In Victoria there was no recent prior circulation of seasonal influenza and thus no temporary immunity to pandemic influenza. There was no association of seasonal influenza vaccine with pandemic influenza infection.

 

In Canada seasonal influenza preceded circulation of the pandemic virus. An unvaccinated proportion of the population developed temporary immunity to pandemic influenza from seasonal infection but a proportion of vaccinated members of the population did not get seasonal infection and hence did not develop temporary immunity to pandemic influenza.

 

It may therefore have appeared as if seasonal vaccination increased the risk of infection with pandemic influenza A(H1N1) virus.

 

 

It’s an attractive theory, and it has been suggested that this form of temporary immunity might even help explain why influenza pandemics tend to come in waves.

 

But it’s just a theory.

 

While results from today’s EID study match well with most of those in the literature, the authors warn that:

 

Additional epidemiologic and experimental investigations are needed to clarify the relationship between TIV use and infection with the pandemic strain.

 

Good science takes time.

 

And that means that while the evidence is currently lopsided against there being a link, more research will be needed before the `Canadian Problem’ can be fully and truly resolved.

»» Read More

ECDC: Annual Risk Assessment On Seasonal Flu 2011-2012

 

 

# 6219

 

Normally by mid-March the northern hemisphere’s flu season is well past peak, and is in decline.  Not so this year, with flu still continuing to surge (albeit at below average levels in many regions) in the latest reports.

 

Additionally, after two very stable years with the H1N1, H3N2, and Victoria B viruses in circulation, this past winter has seen a growing divergence in the H3N2 and B strains, prompting a change in next year’s vaccine recommendations. 

 

The ECDC has produced a 21-page Risk Assessment for the 2011-2012 flu season, which summarizes this flu season to date.

 

 

ECDC publishes its annual risk assessment on seasonal influenza 2011/2012 in Europe

12 Mar 2012

ECDC

On 12 March 2012 ECDC published its annual risk assessment on seasonal influenza 2011/2012 in Europe. ECDC points out that on this occasion the seasonal influenza epidemics in Europe started unusually late and unlike the last few winters have not followed any particular geographical progression.

 

The annual EU season influenza risk assessment follows a structure that was established in the 2009 pandemic and gives an early description of the epidemics of seasonal influenza in the EU/EEA countries drawing on the experience of the first affected countries. The assessment identifies the special features of the current season, especially areas where public health or clinical actions are justified. It also highlights areas of uncertainty and therefore priorities for further work. The first ECDC seasonal influenza risk assessment was published in January 2011.

 

Virological surveillance data for the season shows that the epidemics have so far been dominated by the A(H3N2) viruses, but recently the proportion of B viruses has increased. The data also shows that some A(H1N1)pdm09 viruses are also circulating, although these are far lower in numbers than in the previous two seasons. However, they are over-represented among the people most severely affected that have been hospitalised with a confirmed infection. Antiviral resistance to the neuramindase inhibitors is almost non-existent this season.

 

At this stage, the role that B viruses will play towards the end of the season is uncertain. Other areas of uncertainty are the degree of effectiveness of the seasonal influenza vaccine in a season when there is an imperfect match between the vaccine and the circulating A(H3N2) viruses and the level of premature mortality that can be expected in older people due to the dominance of the virus A(H3N2). It will be difficult to tease apart the effects due to the influenza from those consequences of the cold weather.

Related links:

• See the full ECDC report: ECDC risk assessment on Seasonal influenza 2011/2012 in Europe (EU/EEA countries)

»» Read More

CMAJ: Childhood Flu Vaccinations Reduced Hospitalizations

 

 

# 5855

 

 

From the CMAJ (Canadian Medical Association Journal) we get the results of a comparative study between the United States – which expanded its recommendations for seasonal influenza vaccination to include healthy children aged 24–59 months in 2006-07, and Canada which did not follow suit.

Using data collected on ER visits by children in two pediatric hospitals  located in Boston, Massachusetts & Montréal, Quebec over a period of 9 years, they were able to compare the rates of influenza-like-illness (ILI) among children both before and after the U.S. vaccine policy change went into effect.

 

What they found was that relative to Canada, the U.S. saw a 34% reduction in ILI among children aged 2-4 since the new vaccine recommendations were instituted.

 

The research paper is available on the CMAJ website:

 

Effect of expanded US recommendations for seasonal influenza vaccination: comparison of two pediatric emergency departments in the United States and Canada

Anne Gatewood Hoen, PhD, David L. Buckeridge, MD PhD, Katia M.L. Charland, PhD, Kenneth D. Mandl, MD MPH, Caroline Quach, MD MSc, John S. Brownstein, PhD

 

Interpretation: The divergence in influenza rates among children in the US and Canadian sample populations after institution of the US policy to vaccinate children two to four years of age is evidence that the recommendation of the US Advisory Committee on Immunization Practices resulted in a reduction in influenza-related morbidity in the target group and may have indirectly affected other pediatric age groups. Provincial adoption of the 2010 recommendation of the National Advisory Committee on Immunization in Canada to vaccinate children two to four years of age might positively affect influenza morbidity in Canada.

 

 

For more details, we get this press release from Children’s Hospital in Boston.

 

 

'Natural experiment' documents the population benefit of vaccinating preschoolers against the flu

Flu rates among two- to four-year-olds decline 34 percent following changes in U.S. vaccine policy; study is first to use real time hospital data to evaluate policy change

Boston, Mass. – Recent policies calling for vaccinating preschool-aged children against the flu led to a 34 percent decline in influenza cases in this age group, according to researchers at Children's Hospital Boston and McGill University. The findings, which revealed smaller declines in other age groups as well, arose from a study that used real time surveillance data from pediatric emergency departments (EDs) in the United States and Canada to evaluate the relationship between national flu vaccination policies and rates of flu-like illness.

 

The research team, led by Anne Gatewood Hoen and John Brownstein of the Children's Hospital Informatics Program (CHIP), reported their findings September 19 in the Canadian Medical Association Journal.

 

Preschoolers – specifically children aged two to four – play a significant role in community transmission of the flu with each new season. The Advisory Committee on Immunization Practices – the national body that sets vaccination policies in the U.S. – updated its influenza vaccine recommendations in 2006 to include vaccination of this age group. The corresponding Canadian body, the National Advisory Committee on Immunization, did not include these children in its recommendations until 2010.

 

"The differences in the U.S. and Canadian policies created conditions for a natural experiment for evaluating the effects of U.S. policy change in the target age group," said Brownstein, director of CHIP's Computational Epidemiology Group. "They also gave us an opportunity to test whether we could use hospital-based real time surveillance data to assess the effects of policy changes, and do so more quickly than traditional epidemiologic studies, which are more focused on vaccine uptake than on outcomes."

(Continue . . . )

 

 

As always, there were some limitations to this study. First, it was only conducted at two hospitals, which might not accurately reflect national trends.

 

Second,  that influenza diagnoses were rarely confirmed by lab tests, but were rather based on symptoms of ILIs (influenza-like-Illnesses). The authors state, however, that:

 

Repeating our analysis with a narrower definition of influenza-like illness resulted in a strengthening of the effect from a 34% reduction to  a 52%  reduction in  emergency department visits for influenza-like illness at Children’s Hospital Boston relative  to  the Montreal Children’s Hospital, which suggests that our broad definition resulted in a conservative  estimate of  the effect.

 

And third, data on vaccine uptake for each patient was not generally available, and instead the authors relied upon surveys of vaccination rates among children during the years in question.

 

Still, despite these limitations, this study provides strong evidence to support to the policy of vaccinating young children against seasonal influenza. 

 

With influenza season soon upon us, the CDC  would like to see just about everyone over the age of 6 months get the flu vaccine. 

 

For details on this year’s recommendations see:

 

MMWR: ACIP Updated Flu Vaccination Recommendations

 

The CDC also provides a parent’s guide with information on the danger signs in children, and advice on vaccination.

»» Read More

Already Working On My Antibodies For The Fall

 

 

 

# 4914

 

 

Taking a bit of my own advice (see OK To Get Your Flu Shot Early), yesterday morning I drove down to my local chain pharmacy to get my yearly flu shot.  

 

Admittedly it was 9am on a  Saturday morning, but I was amazed how quickly I was in and out – the whole process took less than fifteen minutes.

 

This year I received a `flu packet’ in the mail from my pharmacy as a reminder, along with a couple of application forms. I filled mine out in advance, saving me a minute or two at the store.

 

Twenty-four hours later, and I’ve no ill effects save a slight ache in my arm last night as I went to bed.  This morning, it has disappeared completely (the ache, not the arm).

 

Hopefully I’m well on my way towards building a nice load of antibodies against this year’s flu strains, and in a couple of weeks I should be pretty well protected.

 

Not 100%, of course.  

 

Vaccines aren’t perfect. But most years they are pretty effective, and despite the daily demonization of them on the Internet, pretty darn safe, too.

 

This year we’ve a new strain of H3N2, one that most of the community probably doesn’t have much immunity to.   H3N2 – unlike last year’s novel H1N1 - is no respecter of age, and this winter may prove burdensome to old codgers like me. 

 

Luckily, the new flu vaccine has antigens against it.

 

So even if you had the pandemic flu last year, or got the H1N1 vaccine, you still need to get a flu shot this year. 

 

The CDC wants you to know:

 

 

The Seasonal Flu Vaccine

A seasonal vaccine is distributed routinely every year.

• While there are many different flu viruses, the flu vaccine protects against the three viruses that research suggests will be most common.
• The 2010-2011 flu vaccine will protect against an influenza A H3N2 virus, an influenza B virus and the 2009 H1N1 virus that caused so much illness last season.
• Everyone 6 months of age and older should get vaccinated against the flu as soon as the 2010-2011 season vaccine is available.
• People at high risk of serious flu complications include young children, pregnant women, people with chronic health conditions like asthma, diabetes or heart and lung disease and people 65 years and older.
• Vaccination of high risk persons is especially important to decrease their risk of severe flu illness.
• Vaccination is important for health care workers, and other people who live with or care for high risk people to keep from spreading flu to high risk people.
• Children younger than 6 months are at high risk of serious flu illness, but are too young to be vaccinated. People who care for them should be vaccinated instead.

 

»» Read More

Australia Lifts Ban On Flu Vax For Under Five’s

 

 

 

# 4769

 

In April of this year, dozens of reports of febrile reactions (sometimes with convulsions) associated with Australia’s seasonal flu vaccine were reported in young kids. 

 

An investigation was launched, and a temporary moratorium declared on vaccinating kids under the age of five.

 

Australia Investigating Adverse Vaccine Reactions

Australian Vaccine Investigation Widens

 

Over time, it became apparent that while the exact reasons for these febrile reactions remained elusive, that the problem was associated only with CSL’s Fluvax, and not with any other manufacturer’s vaccines.

 

Today, the Sydney Morning Herald is reporting that the ban on vaccinating under-fives in Australia has been lifted since these levels of side effects have not been observed in children receiving competing  brands Influvac or Vaxigrip.

 

 

Ban on flu vaccine for young kids lifted

July 30, 2010 - 4:09PM

 

Certainly good news, not only for kids in Australia, but for our own seasonal flu vaccination campaign which is due to kick off in September. 

 

This year’s trivalent flu vaccine will contain antigens for the pandemic A/California/7/2009 (H1N1)-like virus, the newly emerging A/Perth/16/2009 (H3N2)-like virus, and B/Brisbane/60/2008-like Influenza B virus.

 

Although minor adverse affects (usually a mild fever, or localized swelling at the site of injection) are sometimes seen with flu shots, the vaccine itself has proven to be remarkably safe, and most years very effective.

 

Serious side effects are extremely rare.

 

Given the burden of mortality and morbidity that influenza places upon society, the CDC has been moving towards recommending nearly universal voluntary vaccination for those over 6 months of age in recent years.

 

This year, that will be the goal of the vaccination campaign. Lisa Schnirring at CIDRAP brings us the details.

 

CDC launches universal flu vaccination recommendation

Lisa Schnirring Staff Writer

Jul 29, 2010 (CIDRAP News) – The US Centers for Disease Control and Prevention (CDC) today endorsed its vaccine advisory group's recommendation for universal influenza immunization, as public health groups prepare to shift gears from pushing the pandemic H1N1 vaccine to drawing the public's attention to the new seasonal flu vaccine advice.

 

The CDC issued a comprehensive update on seasonal flu vaccination, which includes the new universal recommendation, in an early online edition of Morbidity and Mortality Weekly Report (MMWR). In February the CDC's Advisory Committee on Immunization Practices (ACIP) recommended seasonal flu immunizations for nearly everyone except babies younger than 6 months old.

(Continue . . . )

Jul 29 MMWR report

PKIDSs Online Web site

»» Read More

WHO: Week 25 Virological Update

 

# 4712

 

 

The World Health Organization has released their latest pandemic H1N1 update (#108), current through July 4th.  

 

A brief excerpt from the much longer report:

Worldwide, overall pandemic influenza activity remains low. Active circulation of pandemic influenza virus persists in areas of the tropics, particularly in South and Southeast Asia, the Caribbean and West Africa. Overall pandemic and seasonal influenza activity has remained low during the early part of the current winter season in the temperate zone of the southern hemisphere.

Low levels of seasonal influenza (H3N2 and type B) viruses were detected during June 2010 in South Africa, while Chile, Australia, and New Zealand, have all recently detected low levels of predominantly pandemic influenza virus. Increasing seasonal influenza activity has also recently been observed in several countries of Central America.

 

The virological update – which is perhaps of greater interest – runs a week behind, and deals with June 20th-June 26th.

 

Here is the latest graphic showing the breakdown of virus sampling from selected countries.

 

 

Although the total number of influenza cases remains low,we continue to see scattered reports of the detection of seasonal H3N2 along with the novel H1N1 and influenza B strains.

 

The graph below shows the breakdown of viral specimens in the the southern hemisphere since the start of 2010.

 

Weekly update (Virological surveillance data)

Summary on week 25

• Overall influenza activity has remained at low levels in most parts of the world.
• In the Northern Hemisphere the number of influenza type B virus detections exceeded that of influenza A.
• In the Southern Hemisphere, there is an observation of increasing number of influenza A virus detections with co-circulation of pandemic A(H1N1) and seasonal A(H3N2) viruses.

Global Virological Surveillance

At low levels, influenza B viruses continued to be predominating in some countries and areas of Northern Hemisphere, including China (69.3% of all influenza detections) and Russian Federation (93.7%). Sporadic influenza B activity has also been observed in some other countries.

 

Sporadic influenza A activity was reported in some countries in the Southern Hemisphere, including Australia, Brazil and South Africa. The proportion of A(H3N2) increased in South Africa (53% of all detections) while pandemic A(H1N1) virus was reported as predominant in Brazil (93.8%). In Australia the proportion of co-circulation of pandemic A(H1N1) and seasonal A(H3N2) viruses is very similar (58.3% and 41.7% of all detection, respectively).

 

FluNet Report

The total number of specimens reportedly positive for influenza viruses by National Influenza Centres (NICs) from 29 countries was 356. Of these, 194 (54.5%) were typed as influenza A and 162 (45.5%) as influenza B.

 

From the start of the pandemic in 19 April 2009 to 26 June 2010, the total number of specimens reported positive for influenza by NIC laboratories was 647,378*. Of these, 490,415 (75.8%) were pandemic A(H1N1), 8,946 (1.4%) were seasonal A(H1N1), 33,509 (5.2%) were A(H3N2), 80,737(12.5%) were A (not subtyped) and 33,645(5.2%) were influenza B.

 

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Flu: Down, But Not Completely Out

 

 

 

# 4607

 

 

The CDC released on Friday what they expect to be their last FluView report for the 2009-2010 flu season.  Influenza activity in the United States remains low.

 

While flu surveillance will continue throughout the summer, regular weekly reporting won’t resume until the fall.

 

A brief look at this last report, and a look around the globe at where pandemic H1N1 – and even low levels of seasonal H1 and H3 strains – are still circulating.

 

 

2009-2010 Influenza Season Week 20 ending May 22, 2010

This is the final report of the 2009-2010 season.
The first weekly influenza surveillance report of the 2010-2011 season (week 40, week ending October 9, 2010) will be published on October 15, 2010.

All data are preliminary and may change as more reports are received.

Synopsis:

During week 20 ( May 16-22, 2010), influenza activity decreased in the U.S.

• Two (0.2%) specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division were positive for influenza.
• Both subtyped influenza A viruses were 2009 influenza A (H1N1).
• The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.
• Three influenza-associated pediatric deaths were reported and were associated with 2009 influenza A (H1N1) virus infection.
• The proportion of outpatient visits for influenza-like illness (ILI) was 1.0%, which is below the national baseline of 2.3%. All 10 regions reported ILI below region-specific baseline levels.
• No states reported widespread or regional influenza activity. One state reported local influenza activity. Guam, Puerto Rico, and 13 states reported sporadic influenza activity. The District of Columbia and 34 states reported no influenza activity, and the U.S. Virgin Islands and two states did not report.

 

The CDC’s Key Flu Indicators page has their latest International summary, showing flu trends in selected regions of the world.  Some excerpts below, followed by a brief discussion.

 

 

2009 H1N1 Flu: International Situation Update

May 28, 2010, 5:15 PM ET

This report provides an update to the international flu situation using data collected through May 23, 2010, and reported by the World Health Organization (WHO) on May 28.

The most active areas of 2009 H1N1 influenza transmission are in the tropical regions of the Caribbean and Southeast Asia. In the tropical regions of South America, 2009 H1N1 and seasonal influenza viruses continue to co-circulate at low levels. Influenza B has been reported at low but increasing levels in certain South American countries.  

Selected Highlights

• • According to WHO, the majority of 2009 H1N1 virus isolates tested worldwide remains sensitive to oseltamivir, an antiviral medicine used to treat flu. Among 2009 H1N1 isolates tested worldwide, 290 have been found to be resistant to oseltamivir – 67 of these isolates were detected in the United States.

• Approximately 1% of U.S. 2009 H1N1 viruses tested by CDC since September 1, 2009, have been resistant to oseltamivir.

• Influenza B was reported as the predominating influenza virus accounting for 66.1% of all influenza detections in China (Hong Kong SAR), 84.4 % in the Republic of Korea and 85.1% in the Russian Federation.

  

• Sporadic detections of seasonal influenza A(H1N1) virus were reported in China and the Russian Federation, and influenza A(H3N2) activity has been reported from China, Ghana, Kenya, and Thailand recently.

 

 

The World Health Organization’s most recent pandemic update (#102) describes the global situation this way:

 

The most active areas of pandemic influenza virus transmission currently are in parts of the Caribbean and Southeast Asia, where low level circulation is occurring. Except for localized areas of pandemic influenza activity in parts of Chile, there is little evidence of pandemic influenza activity in the temperate zone of the southern hemisphere.

 

Of note, Respiratory Syncitial Virus (RSV) is widely circulating in South America resulting in an increase in respiratory disease activity, complicating somewhat the interpretation of syndromic surveillance data from the area. RSV primarily affects children under the age of 5 years.

 

Seasonal influenza A viruses continue to be detected at low to sporadic levels in all regions. Influenza B has been reported in increasing but low numbers in South America, where it only recently appeared, while it is decreasing in Asia.

 

 

Of particular interest is the finding that seasonal influenza A viruses continue to be detected at low levels around the world.   These are the H3 and the H1 varieties.  

 

For months, there has been speculation that these strains might disappear completely, as has happened several times in the recent  past when a novel virus has emerged.   

A little pandemic history is in order.

 

Up until 1977, we only saw one influenza `A’ strain in circulation at a time.  And that was – up until that time – thought to be the normal scheme of things. 

 

 

As you can see in the chart above, in 1918 a pandemic of H1N1 supplanted whatever influenza `A’  (possibly H2N2) was circulating before that time, and for the next 40 years, it was believed to be the solitary `A’ strain in the wild.

 

In 1957, a new reassorted virus (H2N2) emerged with the Asian Flu, and even though it was a relatively mild pandemic, it very quickly replaced the H1N1 virus.

 

Again, just eleven years later, a new virus (H3N2) arrived in the form of the Hong Kong Flu, and the (now seasonal) H2N2 was no more.

 

Each time a new virus appeared, it drove out the competition.  Exactly why?  Well . . . we don’t really know why. 

 

But that was the pattern. 

 

Until 1977.  That year an old foe, in the form of the H1N1 virus, re-appeared after a 20 year absence.

 

How and why it returned is a mystery, although many believe it was the result of an accidental release from a Russian research laboratory.It was dubbed the `Russian Flu’, and quickly spread among the under-20-somethings who had no immunity.

 

But this time things were different. It didn’t replace or drive out the existing (H3N2) virus.

The reason most commonly given is that older people were less affected by the returning H1N1 virus – since those born before 1957 had previous exposure – and so they remained a reservoir of the H3N2 virus.

 

The two strains (H3N2 and H1N1) co-circulated, and for the past 33 years having two main `A’ strains in circulation (along with some `B’ viruses) has been the norm.

 

Once again, we are faced with the introduction of a new virus, the novel H1N1, and once again it has a predilection for those born after about 1957.

 

 

A bit surprisingly, the existing seasonal `A’ strains (H3N2/H1N1) all but disappeared from surveillance reports last fall despite there being an ample reservoir of 60+ year olds out there that are less affected by H1N1 and vulnerable to the older strains.

 

Now that pandemic flu activity has declined, surveillance has begun to pick up sporadic cases of the older seasonal H1N1 and H3N2 viruses again.   

 

The actual number detected remains small.

 

Whether this means that there remains a viable reservoir of these older influenza A strains, and we might see a resurgence of regular H1N1 or H3N2 next year, is too soon to answer.

 

This may simply be seasonal H3’s and H1’s `last gasp’, so to speak.

 

But as long as there are any of these seasonal viruses in circulation the potential for their return exists. 

 

And some scientists believe that as the number of susceptible hosts for a flu virus diminish, evolutionary pressures build upon the virus to mutate if it is to survive.  

 

Whether that theory holds true this time is, again, too soon to say. 

 

So, as this flu season comes to an end in the Northern Hemisphere, we are left with a bit of a cliffhanger. One filled with many unanswered questions and numerous possibilities for next fall. 

 

While we’ll be watching the tropics and the southern hemisphere for clues over the next few months, solid answers are likely to remain elusive until we actually see what happens next fall and winter.

 

Stay tuned.

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Referral: Seasonal Flu Waves in the US

 

 

# 4506

 

 

While the day-to-day flu news remains slow, we are seeing a good deal of influenza research coming online.   More than can be adequately addressed by any one blogger.

Fortunately, we’ve  a community of terrific  bloggers (see my sidebar) to carry the load.

 

Last week there was a press release on research that studied the progression of (seasonal) flu waves across the United States.  I mentally filed it away with the intention of mentioning it at some point, but promptly forgot about it.

 

Luckily, Jimmy Jazz at the Break Glass blog was more diligent than I in following up on this story.

 

Read:       Seasonal Flu Waves in the US

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Whither Influenza?

 

# 4349

 

 

 

 

 

Influenza A today appears to be at a crossroads, with the H1N1v (variant) virus largely in retreat and no signs (yet) of a resurgence of the seasonal strains we’ve been saddled with for the past three decades.

 

And that begs the question – what happens next?

 

I will confess at the outset, I don’t know the answer to this question, and so I’ll be making no predictions. But that doesn’t mean we can’t discuss some of the possibilities. 

 

And there are, quite frankly,  a lot of possibilities  . . .

 

The most likely scenario right now seems to be that the novel H1N1 virus will settle in over the coming months as our dominant seasonal flu strain and remain so until something `more fit’ - to which mankind is susceptible - comes along to knock it off its perch.

 

But likely scenarios are perilous things.

 

If you had asked a year ago what the next twelve months would bring, few scientists would have dared suggest that a `weak sister’ H1N1 virus would leap forth from pigs to humans in (of all places) North America, sweep across the world in record time as a high morbidity-low mortality pandemic, and drive out the other seasonal strains along the way.

 

Even if this `most likely scenario’ holds true, there are a lot of avenues it could follow.   To simply say it becomes a `seasonal flu’ is to leave out a lot of detail.

 

Will its virulence change, or will it begin to impact the elderly population more over time?

 

Professor Ian York who pens the Mystery Rays blog commented on here yesterday that between vaccinations and acquired immunity `nearly 3/4 of children, and over half of adults, should now be immune to the swine-origin H1N1’  (US numbers) which is a pretty good step towards `herd immunity’.  

 

Enough so that it casts doubt on whether we will see a major resurgence of the virus this spring in North America. 

 

Once we get good seroprevalence studies of the general population, we’ll have an even better idea of our level of immunity in the wake of this pandemic. 

 

Unknown right now is the incidence of asymptomatically acquired immunity.

 

Which raises interesting questions for next fall as well. 

 

As we as a society grow closer to acquiring `herd immunity’  the virus must either mutate or `drift’ antigenically to evade that immunity, or it will eventually run out of hosts and die.

 

My good friend Scott McPherson gives us a great run down of this scenario, along with the concerns of Professor John Oxford, in his latest screed entitled Parsing the numbers on the latest CDC H1N1 swine flu report.

 

A mutation or drift in the H1N1v virus seems likely, but the question is . . .  how long with that take?  

 

Will it happen during the Southern Hemisphere’s upcoming flu season?   Or will the virus lay low next year, like it did in the year following the 1957 pandemic, only to rise again a year or two later?

 

We’ve less than 100 years of scientific observation of flu viruses to draw upon, and as H5N1 and H1N1v have shown, the `rules’ we thought we understood about influenza are subject to change.

 

If H1N1v fails to mount an aggressive return in the fall of 2010, will that leave the door open to other viruses to take its place?  

 

Influenza, even in a normal year,  represents less than 20% of all flu-like illnesses.  

 

Coronaviruses, metapneumovirus, parainfluenzavirus, respiratory syncytial virus (RSV), any of the myriad Rhinoviruses (Common cold), and some adenoviruses can all cause ILI’s, or influenza-like illnesses.

 

Even last October – near the height of the pandemic wave in the United States – (see ILI’s Aren’t Always The Flu) more than 70% of the samples submitted to the CDC proved to be something other than influenza A.

 

 

In the absence of H1N1v, could 2010 become a big B influenza year?  Or a year where RSV or an adenovirus is the major player?  

 

If you take influenza A out of the equation, does that give some other virus a competitive advantage? 

 

The dynamic between these viruses isn’t well understood, just as it isn’t clear how a novel strain like H1N1v managed to pretty much take out seasonal H3N2, even though there remains a susceptible population to it.

 

Does a waning H1N1v leave the door open for a return of the the H1 and H3 seasonal viruses?  And if not, in the absence of other influenza A viruses, does this convey to H5N1 or any of the H7 or H9 avian influenza viruses any sort of evolutionary advantage?

I don’t think anyone really knows.  

 

But it is going to be fascinating to watch.

 

And just as the rules of influenza appear to be malleable and subject to change, so too is Flublogia – that little Internet world comprised of flu forums, newshounds, and flu blogs that sprang up roughly five years ago in response to the SARS and bird flu threats.

 

Crof, Scott, and I have all strayed from flu-centric topics in the past, and with a variety of emerging infectious diseases out there deserving of our attention, I expect you’ll see a good deal more of that in the future. 

 

The Reveres at Effect Measure, Vince Racaniello at Virology Blog, Maryn McKenna of Superbug Blog, and Ian York at Mystery Rays have always been eclectic health/science bloggers, and the flu forums like Flu Wiki and FluTrackers (among others) have watched other disease threats for years.

 

While I can’t predict with any confidence what direction influenza will take over the next year or two, I am confident that we will have no lack of important health and science topics to write about in the months and years to come.

 

MRSA, Malaria, C. Dif, Dengue, Chikungunya, Ebola, TB, HIV/AIDS, Cholera, Hendra, Nipah, Small Pox, Bubonic Plague, Lassa Fever, Marburg, SARS, RSV, along with dozens more . . . and yes, even Pathogen X – the one we’ve yet to identify – are all worth our notice.

 

 

Along with influenza, of course.

 

Rest assured, that with or without a pandemic.

 

Flublogia marches on.

 

         *     *     *      *      *     *     *      *     *

 

A brief personal note:

 

As today’s blog illustrates, much of what I write about is inspired by what I read and learn from other sources.  No blogger is an island, and that is particularly true in Flublogia.

 

While I’ve been pondering the issues I wrote about today for some time, they only solidified into a blog post after reading Ian York’s comments yesterday, Scott’s blog last night, several recent entries from Crof, and having had conversations with several others in Flublogia in recent days.

 

A more collegial group you’d be hard pressed to find, and I owe them a large debt of thanks.   You’ll find I name names in Reliable Sources in FluBlogia, so I’ll spare you a detailed list today. 

 

Collectively they’ve proved that difficult subjects like pandemics, emerging infectious diseases, and natural disasters can be discussed reasonably, scientifically, and without shrill overtones or alarmism. 

 

And that is something we need more of on the Internet. 

»» Read More

Looking Ahead To The Rest Of The Flu Season

 

 

# 4164

 

 

What happens next with the 2009-2010 flu season is a big, open question.  One that I recently wrote about in Waiting For The Other Flu To Drop.    

 

 

With more than 4 months of our traditional Northern Hemisphere flu season remaining, will we see a return of seasonal flu?

 

Or will novel H1N1 supplant them, as H3N2 did in 1968, H2N2 did in 1957, and H1N1 did in 1918?

 

Today Bloomberg News has a long, and informative report on the prospects of seeing a return of the seasonal viruses this year.  It features interviews with a number of well known names in the flu world, including Harvard’s Marc Lipsitch, University of Michigan’s Arnold Monto, and Vanderbuilt’s William Schaffner.

 

While nothing is writ in stone at this point, with each passing day it appears less likely that we will see a resurgence of seasonal flu this year.   

 

Of course . . . Influenza is, as they say, unpredictable. 

 

And even if H1N1 supplants the other influenza `A’ strains, the future of influenza `B’ seems less clear.

 

The flu season isn’t over until it’s over.   And as last summer proved, sometimes it isn’t over even then.

 

This from Bloomberg News.

 

 

Swine Flu May Mean Seasonal Strain Won’t Emerge in U.S. Winter

 

By Tom Randall

Dec. 17 (Bloomberg) -- Seasonal flu, which annually kills 30,000 Americans, may not appear in the U.S. for the first time in more than 40 years, crowded out by the swine flu pandemic and mass vaccination campaigns.

 

Seasonal strains are almost nonexistent in reports from countries where swine flu, or H1N1, has taken hold. In the U.S. and Europe, 99 percent of influenza cases tested last week were H1N1, according to government reports. Seasonal versions of virus that usually arrive in December and peak in February may not emerge at all, said Marc Lipsitch, a flu tracker at the Harvard School of Public Health, in Boston.

 

“I would bet against a seasonal flu this year,” said Lipsitch, a professor of epidemiology, in a telephone interview. “But I wouldn’t bet very much money.”

 

One of the seasonal strains most likely to appear this year, known as type B, was responsible for 7 of 478 positive cases in a testing sample for the week ended Dec. 5, according to the U.S. Centers for Disease Control and Prevention. A second form, H3N2, hasn’t been spotted at all.

 

(Continue . . . )

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BMJ: A Review Of Tamiflu’s Efficacy Against Seasonal Influenza

 

 

# 4136

 

 

Today the BMJ (British Medical Journal) tackles a controversial, and oft times contentious, subject.  Whether Tamiflu is of sufficient benefit to warrant its widespread use against seasonal influenza.

 

This is part of an ongoing review of the existing literature.

 

This review is of Oseltamivir’s use against seasonal influenza in otherwise healthy adults.  The use of Tamiflu against pandemic strains of influenza, or in patients with underlying conditions, isn’t directly addressed here.

 

You’ll find, after reading this research, that there remain many unresolved questions regarding the efficacy of Tamiflu. Hence the use of a question mark (?) in the BMJ title below.  

 

This review raises more questions than it answers.   Some excerpts below (reparagraphed for readability).

 

 

Pandemic influenza

The truth about Tamiflu?

 

This Cochrane group's update of a 2005 review of oseltamivir in pandemic influenza concludes:

 

"Neuraminidase inhibitors have modest effectiveness against the symptoms of influenza in otherwise healthy adults. The drugs are effective postexposure against laboratory confirmed influenza, but this is a small component of influenza-like illness, so for this outcome neuraminidase inhibitors are not effective.

 

Neuraminidase inhibitors might be regarded as optional for reducing the symptoms of seasonal influenza. Paucity of good data has undermined previous findings for oseltamivir's prevention of complications from influenza.

Independent randomised trials to resolve these uncertainties are needed."

 

 

A cluster of articles on bmj.com seeks to elucidate problems with the data that have underpinned the use of oseltamivir in healthy adults with pandemic influenza.

 

Deborah Cohen retraces the steps of the Cochrane reviewers as they tried to obtain all the relevant data and finds that commitments to transparency are still in doubt.

 

Peter Doshi explains that the public evidence base for this global public health drug is fragmented and inconsistent.

 

And Nick Freemantle and Mel Calvert find that observational studies of oseltamivir's efficacy show minimal benefit. In an accompanying editorial, Fiona Godlee and Mike Clarke say that the full data from drug trials must be available for scrutiny by the scientific community.

 

Read also:

• Roche replies to the authors of the Cochrane review on oseltamivir.
• Roche's point-by-point response to BMJ questions
• Editor's choice: We want raw data, now

 

 

Published 8 December 2009, doi:10.1136/bmj.b5106
Cite this as: BMJ 2009;339:b5106
Research

Neuraminidase inhibitors for preventing and treating influenza in healthy adults: systematic review and meta-analysis

 

While the entire study is worth reading, the bottom line is there is insufficient evidence, according to the authors, to conclude either for or against Tamiflu for use in healthy adults with seasonal influenza.

 

In other words, more studies are needed.

 

Regarding its use against pandemic strains, the authors state:

 

Role of neuraminidase inhibitors in pandemic influenza

We identified no direct comparative evidence of the role of neuraminidase inhibitors in avian influenza A/H5N1 or in the current novel influenza A/H1N1 pandemic. This means that we have to generalise from the trials, and this seems reasonable given that the pandemic influenza A/H1N1 virus will likely be acted on in the same biological manner as previously circulating influenza viruses, such as seasonal A/H1N1.

 

Neuraminidase inhibitors do not, however, prevent infection or stop nasal viral excretion, so they may be a suboptimal means of interrupting viral spread in a pandemic. If used to contain a severe pandemic outbreak, neuraminidase inhibitors should be considered only part of a package of measures to interrupt spread, including physical measures.

 

You’ll find Roche’s response to this research, and to questions raised by the BMJ, along with an editorial statement, but some of these items will require a subscription to the BMJ to access. 

 

The research, however, is freely available.

 

MSNBC quotes the World Health Organization:

They said data from countries around the world show that when given early, Tamiflu can reduce the severity of swine flu symptoms, though the agency recommends the drug be saved for people at risk of complications, like pregnant women, the elderly, children, and those with underlying medical problems.

 

"This will not change our (Tamiflu) guidelines," said Charles Penn, a WHO antivirals expert. Penn said that while past studies show Tamiflu only has a modest benefit, when patients with severe illness or at risk of complications are treated early, there are fewer hospitalizations and deaths.

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