BMJ: H1N1 Vaccination & Fetal Death Rates

Photo Credit – CDC

 

# 6311

 

 

One of the persistent myths on the internet is that the 2009 H1N1 vaccine was responsible for `thousands’ of miscarriages. One need only Google `Vaccine + Miscarriage’ to see some of the propaganda out there.

 

It is a sad but true statistic that in the United States about 1 million women experience a miscarriage every year. That works out to be about 2,500  miscarriages each day.

 

And if we could vaccinate all of the pregnant women in the country today, tomorrow 2500 would still miscarry.

 

And most would probably blame the vaccine.

 

There is no such thing as a 100% benign drug, and so the possibility exists that a vaccine could produce serious adverse side effects. Which is why monitoring systems like VAERS are utilized to try to detect any spike in adverse effects from vaccines.

 

Over the past 3 years we’ve seen very encouraging reports on the safety of the 2009 pandemic vaccine. Last October in Lancet: Guillain-Barré Syndrome & H1N1 Vaccine In Children) we learned:

 

Surveillance and reporting systems have not found any unusual pattern of deaths in the United States attributable to the pandemic vaccine, and the oft predicted spike in Guillain-Barré syndrome (GBS) never occurred (see CIDRAP VAERS study finds H1N1 vaccine safety similar to seasonal vaccines').

In fact, the VAERS report cited above found 0 deaths they could link to the pandemic Vaccine. Meanwhile, during the same period the CDC estimated that at least 12,000 (mostly younger) Americans died from the flu.

 

 

And today, in the BMJ, we’ve another study of a large cohort of pregnant women in Demark that reassuringly finds no increase in miscarriage among those who received the 2009 H1N1 vaccine.

 

 

Vaccination against pandemic A/H1N1 2009 influenza in pregnancy and risk of fetal death: cohort study in Denmark

Published 2 May 2012  BMJ 2012;344:e2794

Abstract (excerpt)

Results The cohort comprised 54 585 pregnancies; 7062 (12.9%) women were vaccinated against pandemic A/H1N1 2009 influenza during pregnancy. Overall, 1818 fetal deaths occurred (1678 spontaneous abortions and 140 stillbirths). Exposure to the H1N1 vaccine was not associated with an increased risk of fetal death (adjusted hazard ratio 0.79, 95% confidence interval 0.53 to 1.16), or the secondary outcomes of spontaneous abortion (1.11, 0.71 to 1.73) and stillbirth (0.44, 0.20 to 0.94). Estimates for fetal death were similar in pregnant women with (0.82, 0.44 to 1.53) and without comorbidities (0.77, 0.47 to 1.25).

 

Conclusion This large cohort study found no evidence of an increased risk of fetal death associated with exposure to an adjuvanted pandemic A/H1N1 2009 influenza vaccine during pregnancy.

 

 

This latest study closely matches the findings of other researchers, such as we saw in  Hong Kong: No Increase In Fetal Death Among Vaccine Recipients.

 

Ironically, while some seek to demonize the flu vaccine as causing fetal deaths, in October of last year in UK: Pregnancy And Swine Flu a study conducted at Oxford University by the National Perinatal Epidemiology unit found a strong link between infection with the 2009 `swine’ flu and an increased number of stillbirths.

 

Fetal deaths among women infected with the H1N1 virus were 5 times higher than normal.

 

Very early into the 2009 H1N1 outbreak – even before the declaration of a pandemic by the World Health Organization – it became apparent that pregnant women were making up a disproportionate number of ICU admissions for influenza, and deaths.

 

Which is a pattern we’ve seen in pandemic outbreaks in the past (see Pregnancy & Flu: A Bad Combination).

 

 

The truth is, the flu virus is a far greater danger to pregnant women and their unborn child than the vaccine.

 

While the CDC and other public health entities continue to stress the importance of seasonal flu vaccination for pregnant women, there remains reluctance among some pregnant women to get the shot.

 

Vaccines are drugs, and there is no such thing as a 100% safe and 100% effective drug. Even taking over-the-counter medicines entail some risks.

 

But the evidence continues to show that flu vaccines are among the safest drugs available, and that most years they can provide decent protection against a serious and potentially deadly illness.

 

For more reassuring research on the safety profile of modern flu vaccines, you may wish to revisit the following blogs:

 

Harvard Study Reaffirms Safety Of Flu Vaccine

MJA: Safety Of Flu Shot In Young Children

NEJM: Study On China’s H1N1 Vaccine Safety

Lancet: Immunogenicity and safety Of Adjuvanted Flu Vaccines

»» Read More

BMJ: Another Pandemrix Study To Ponder

 

 

Photo Credit CDC 

 

# 5897

 

Whenever there is a hint or a suggestion that a vaccine might have caused some sort of serious side effect, it invariably becomes big news. 

 

Even when the reports are preliminary, and the evidence less than rock solid, these stories often end up on the front pages of newspapers and quickly become fodder for the anti-vaccination brigade.

 

When more reassuring vaccine studies come out, they rarely get that kind of media play, since it isn’t the sort of thing that sells newspapers. 

 

Case in point:

 

A little over a year ago GSK’s Pandemrix vaccine was associated with a perceived increase in narcolepsy among children and adolescents in Finland. For early coverage of this story, you may wish to revisit Finland Suspends Use of Pandemrix Vaccine and EMA To Review Pandemrix Vaccine, both of which I wrote in August of 2010.

 

Despite some conflicting and incomplete data the European Medicines Agency issued a statement last July recommending:

 

In persons under 20 years of age Pandemrix to be used only in the absence of seasonal trivalent influenza vaccines, following link to very rare cases of narcolepsy in young people.

 

Finland also convened a Narcolepsy Task Force (see Finland: Task Force Report On Pandemrix-Narcolepsy Link) that confirmed an association – as yet unexplained  – between receipt of the vaccine and an increase in narcolepsy in children between the ages of 4 and 19.

 

Complicating matters, more than a dozen countries reported an increase in narcolepsy during the 2009 pandemic, even those where the adjuvanted vaccine was not used.

 

You can find details on one such study in Stanford Study Finds Influenza – Narcolepsy Connection  that linked narcolepsy not to the vaccine . . . but to infection by influenza virus itself.

 

Confused yet?

 

Alas, science isn’t always neat and tidy.  Good studies take time, and we don’t always get consistent results.

 

Today, we’ve another study that appears in the BMJ that is a bit more reassuring on the safety of the Pandemrix vaccine, but fails to answer the question of narcolepsy. 

 

It is called:

 

Neurological and autoimmune disorders after vaccination against pandemic influenza A (H1N1) with a monovalent adjuvanted vaccine: population based cohort study in Stockholm, Sweden

OPEN ACCESS

Carola Bardage, epidemiologist, Ingemar Persson, professor of pharmacoepidemiology and senior expert, Åke Örtqvist, county medical officer and associate professor, Ulf Bergman, professor of pharmaco-epidemiology and clinical pharmacologist, Jonas F Ludvigsson, paediatrician and epidemiologist, Fredrik Granath, senior biostatistician

 

This was a population based cohort study conducted in Stockholm, Sweden during the 2009 pandemic where 1,024,019  people were vaccinated with the Pandemrix vaccine and 921,005 remained unvaccinated.

 

Using the detailed healthcare registers for Stockholm County Council, researchers tracked all admissions to hospitals and visits to specialists for autoimmune or neurological diagnoses.

 

The conditions flagged in this study included:

 

• Guillain-Barré syndrome
• Bell’s palsy
• multiple sclerosis
• polyneuropathy
• anaesthesia or hypoaesthesia
• paraesthesia
• narcolepsy
• rheumatoid arthritis
• inflammatory bowel disease (ulcerative colitis, Crohn’s disease)
• type 1 diabetes

 

This study further divided this cohort into those who received the vaccine within the first 45 days of its availability, and those who received it later. Those in high risk groups, with comorbid conditions, were more likely to be vaccinated during the first 6 weeks of the vaccination campaign. 

 

The results (which are far more detailed in the open access report) indicated:

 

Conclusions

Results for the safety of Pandemrix over 8-10 months of follow-up were reassuring —notably, no change in the risk for Guillain-Barré syndrome, multiple sclerosis, type 1 diabetes, or rheumatoid arthritis.

 

Relative risks were significantly increased for Bell’s palsy, paraesthesia, and inflammatory bowel disease after vaccination, predominantly in the early phase of the vaccination campaign.

 

Small numbers of children and adolescents with narcolepsy precluded any meaningful conclusions.

 

The report summary states:

 

What is already known on this topic

• Studies are lacking on adverse events (except for narcolepsy) with any of the three vaccines used in the European Union against H1N1 during the pandemic period

• Available data are limited to case series or highly selected populations with short follow-up or no control group

What this study adds

• Excess risks for Bell’s palsy, paraesthesia, and inflammatory bowel disease after H1N1 vaccination with adjuvanted Pandemrix in Sweden were small but significant among more than one million vaccinated, but only in high risk groups targeted for early vaccination and who were likely to have earlier comorbidity

• The risk of Guillain-Barré syndrome, multiple sclerosis, type 1 diabetes, and rheumatoid arthritis remained unchanged

• Small numbers of children and adolescents with narcolepsy precluded any meaningful conclusions

 

While the low number of children and adolescents with narcolepsy may have precluded making any firm conclusions, their scarcity is nonetheless a bit reassuring.

 

The authors suggest that the small, but statistically significant increase in Bell’s palsy, paraesthesia, and inflammatory bowel disease among the early recipients of the vaccine may be partly, or perhaps entirely, explained by the higher number of high risk patients in that cohort.

 

We are still left with the mystery of what caused the increase in narcolepsy reported in Finland, of course. And there will no doubt be additional studies that will look at the safety of the Pandemrix vaccine in other regions.

 

But for now, as the authors state,  the news is `reassuring’.

 

For previous reports on the safety of (adjuvanted and unadjuvanted) flu vaccines, you may wish to revisit.

 

IOM Report On Vaccine Safety Concerns

 

BMJ: No Substantial Link Between Flu Vaccines And Guillain-Barre Syndrome

 

Lancet: Immunogenicity and safety Of Adjuvanted Flu Vaccines

 

NEJM: Study On China’s H1N1 Vaccine Safety

 

Harvard Study Reaffirms Safety Of Flu Vaccine

 

»» Read More

BMJ Open Study: Self Diagnosis During A Pandemic

 

 

 

Photo Credit CDC Influenza Home Care Guide

 

# 5837

 

We’ve a new study appearing in BMJ Open that looks at just how accurate self diagnosis of influenza during the 2009 pandemic really was.

 

First, a little background.

 

ILIs  . . .  or  Influenza-like Illnesses are among the  most common maladies reported to doctors each year, and while often attributed to `flu’, the causes extend far beyond influenza.

 

The symptoms generally include fever, cough, and body aches  -  but may also commonly include rhinitis, sneezing, headache, fatigue, sore throat, nausea & vomiting, and diarrhea.

 

Influenza A & B, which get most of the headlines, are only responsible for a fraction of the cases of ILI each year. Some estimates put that share as low as 10%.

 

According to the CDC, each year adults (on average) experience 1 to 3 bouts with an ILI, while children may see 3 to 6 flu-like illnesses (cite MMWR)

 

Most of these viral infections are mild, self-limiting, and are almost never identified since testing (beyond, perhaps, a rapid influenza test) is rarely warranted. 

 

Which is why doctors generally refer to ILIs, or Influenza-like Illnesses (or sometimes ARI Acute Respiratory Infection), when making a clinical diagnosis.

 

If an ILI is mild, most people chalk it up to the `common cold’, and if it is more debilitating, figure it is `the flu’.

 

But in reality the spectrum of common respiratory viruses is far more diverse; metapneumovirus, parainfluenzavirus, coronaviruses, respiratory syncytial virus (RSV), enteroviruses, any of the myriad Rhinoviruses  (Common cold), and a number of varieties of adenovirus.

 

 

The prevalence of these non-flu ILI’s complicate the job for doctors and public health officials during a pandemic when limited resources (hospital beds, antivirals, etc) must be prioritized and people must decide whether to go to the ER or self isolate if symptomatic.

 

Which brings us to today’s study, where researchers surveyed more than 1100 people from New Zealand during the 2009 pandemic and compared their perception of whether they caught the flu that year with blood tests showing antibodies to the novel H1N1 virus.

 

 

Self-diagnosis of influenza during a pandemic: a cross-sectional survey

Annemarie Jutel1, Michael G Baker2, James Stanley2, Q Sue Huang3, Don Bandaranayake4

BMJ Open 2011;1:e000234 doi:10.1136/bmjopen-2011-000234

Abstract

Background Self-diagnosis of influenza is an important component of pandemic control and management as it may support self-management practices and reduce visits to healthcare facilities, thus helping contain viral spread. However, little is known about the accuracy of self-diagnosis of influenza, particularly during pandemics.

Methods We used cross-sectional survey data to correlate self-diagnosis of influenza with serological evidence of 2009 pandemic influenza A(H1N1) infection (haemagglutination inhibition titres of ≥1:40) and to determine what symptoms were more likely to be present in accurate self-diagnosis. The sera and risk factor data were collected for the national A(H1N1) seroprevalence survey from November 2009 to March 2010, 3 months after the first pandemic wave in New Zealand (NZ).

Results The samples consisted of 318 children, 413 adults and 423 healthcare workers. The likelihood of being seropositive was no different in those who believed they had influenza from those who believed they did not have influenza in all groups.

Among adults, 23.3% (95% CI 11.9% to 34.7%) of those who reported having had influenza were seropositive for H1N1, but among those reporting no influenza, 21.3% (95% CI 13% to 29.7%) were also seropositive.

Those meeting NZ surveillance or Ministry of Health influenza case definitions were more likely to believe they had the flu (surveillance data adult sample OR 27.1, 95% CI 13.6 to 53.6), but these symptom profiles were not associated with a higher likelihood of H1N1 seropositivity (surveillance data adult sample OR 0.93, 95% CI 0.5 to 1.7).

Conclusions Self-diagnosis does not accurately predict influenza seropositivity. The symptoms promoted by many public health campaigns are linked with self-diagnosis of influenza but not with seropositivity. These findings raise challenges for public health initiatives that depend on accurate self-diagnosis by members of the public and appropriate self-management action.

 

I’ve only printed excerpts from the abstract, but the entire study is open access, and freely available.  The key finding (below) is well illustrated by one of the charts accompanying the study:

 

The likelihood of being seropositive was no different in those who believed they had influenza from those who believed they did not have influenza in all groups.

 

 

In this study, roughly 75% of the people who thought they caught the pandemic flu that fall did not.  While nearly 25% who believed they had not contracted the virus actually had.

 

Even among healthcare workers, the percentage who correctly diagnosed themselves with the pandemic flu was only 33%.

 

And those who reached the conclusion that they had contracted the flu after consultation with a healthcare professional were wrong most of the time as well. 

 

 

Not only can the misidentification of influenza cause serious problems during a pandemic, it also likely skews the public’s perception of the effectiveness of the yearly flu vaccine.

 

Many people complain that in years when they got the shot they still caught the flu. As this study shows, people often mistake non-flu ILIs (which are not covered by the shot) for influenza.

 

The major implication here is that during a pandemic, the majority of people seeking antivirals or medical care due to having flu-like symptoms are likely not to have the pandemic virus.

 

The authors of this study conclude:

 

These findings reinforce public health advice during the pandemic that patients should seek medical care on the basis of disease severity rather than for the purpose of diagnosis.

 

Of course, getting the public to go along with this advice during an influenza pandemic is going to be a lot easier said than done.

»» Read More

BMJ: No Substantial Link Between Flu Vaccines And Guillain-Barre Syndrome

 

 

Photo Credit PHIL

 

 

# 5688

 

The supposed link between flu vaccines and Guillain-Barre Syndrome (GBS) goes back to the 1976 swine flu scare and vaccination drive, where it was estimated that roughly 1 in 100,000 vaccine recipients developed the neurological disorder.

 

The vaccination program was halted after 40 million Americans received the vaccine, several hundred developed GBS, and the expected pandemic failed to show.

 

I was a young paramedic at the time, and chronicled my part in that bit of influenza history some time ago in Deja Flu, All Over Again. 

 

 

In the years since, while there has been little or no evidence of flu shots causing GBS, there remains a palpable level of public concern over vaccines – fears that anti-vaccine activists have played heavily upon in recent years.

 

The CDC, along with many other public health agencies, have allowed that the flu vaccine might carry with it a very low risk of developing GBS.

 

But most years the incidence is so low (perhaps 1 in 500,000 or 1 in a million) as to be nearly impossible to measure.

 

This from the CDC’s Guillain-Barré syndrome (GBS)  Q&A page.

 

What causes GBS?

Many things can cause GBS; about two-thirds of people who develop GBS symptoms do so several days or weeks after they have been sick with diarrhea or a respiratory illness. Infection with the bacterium Campylobacter jejuni is one of the most common risk factors for GBS.

 

People also can develop GBS after having the flu or other infections (such as cytomegalovirus and Epstein Barr virus). On very rare occasions, they may develop GBS in the days or weeks after getting a vaccination.

 

 

Which brings us to a new study appearing yesterday in the BMJ (British Medical Journal) that looks at adjuvanted and unadjuvanted vaccine recipients across 5 European countries in 2009, and once again finds `no substantial link’ between taking the vaccine and GBS.

 

First some excerpts from the study, then I’ll return with more.

 

BMJ 2011; 343:d3908

• Research

Guillain-Barré syndrome and adjuvanted pandemic influenza A (H1N1) 2009 vaccine: multinational case-control study in Europe

OPEN ACCESS

Jeanne Dieleman,Silvana Romio, Kari Johansen, Daniel Weibel, Jan Bonhoeffer,Miriam Sturkenboom,

Abstract

Objective To assess the association between pandemic influenza A (H1N1) 2009 vaccine and Guillain-Barré syndrome.

 

Design Case-control study.

 

Setting Five European countries.

 

Participants 104 patients with Guillain-Barré syndrome and its variant Miller-Fisher syndrome matched to one or more controls. Case status was classified according to the Brighton Collaboration definition. Controls were matched to cases on age, sex, index date, and country.

 

Main outcome measures Relative risk estimate for Guillain-Barré syndrome after pandemic influenza vaccine.

 

<SNIP>

 

Conclusions The risk of occurrence of Guillain-Barré syndrome is not increased after pandemic influenza vaccine, although the upper limit does not exclude a potential increase in risk up to 2.7-fold or three excess cases per one million vaccinated people.

<SNIP> 

The authors conclude by stating:

 

Adjuvanted pandemic influenza A (H1N1) 2009 vaccines did not increase the risk of Guillain-Barré syndrome substantially, if at all.

 

While this study cannot state with absolute scientific certainty that the 2009 pandemic flu vaccine never caused a single case of GBS, they were unable to find any compelling statistical evidence that it did.

 

The qualifier of a `substantial link’  is used because, quite frankly, once you get down to an incidence rate as low as 2 or 3 cases out of a million, adverse effects can be almost impossible to detect.

 

Since viral infections can spark GBS, this study found that vaccination may actually have prevented some cases of Guillain Barre Syndrome – although those numbers are also too low to effectively measure.

 

Just under a year ago, in Lancet: The Influenza - Guillain Barré Syndrome Connection I wrote about a study where the authors stated that the risks of contracting GBS from the vaccine appear to be minor compared to the risks of developing GBS from catching the flu virus itself.

Like all studies, this BMJ study was subject to certain limitations, and additional studies are underway.  It is, however, the latest in a long list of reassuring research on the safety of flu vaccines. 

 

Of course, no vaccine (or drug) can be said to be 100% safe – and so rare but sometimes serious adverse effects have been reported.

 

As an example, there is an investigation in Europe into a possible link between the Pandemrix vaccine and a small number of cases of narcolepsy.

 

But then, even over-the-counter aspirin and NSAIDs contribute to thousands of hospitalizations and deaths each year.

 

It’s all about relative risks. 

 

And the risks from getting influenza – which kills tens of thousands every year - far exceed whatever slim risks that might be posed by getting the flu shot.

 

For more reassuring research on the safety profile of modern flu vaccines, you may wish to revisit the following blogs:

 

Harvard Study Reaffirms Safety Of Flu Vaccine

MJA: Safety Of Flu Shot In Young Children

NEJM: Study On China’s H1N1 Vaccine Safety

Lancet: Immunogenicity and safety Of Adjuvanted Flu Vaccines

 

The preponderance of evidence continues to support the scientific consensus that flu vaccines are very safe and most years, reasonably effective. 

»» Read More

BMJ: Perinatal Outcomes After Maternal 2009/H1N1 Infection

 

 

# 5631

 

 

Even before the novel H1N1 virus emerged in the Spring of 2009, pregnancy was considered to be a significant risk factor during an influenza pandemic.  

 

Researchers knew that during the 1918 pandemic an abnormally high number of pregnant women died from the the Spanish Flu, and those that survived endured a very high miscarriage rate.

 

Even during the much milder 1957 Asian Flu, pregnant women reportedly suffered disproportionately higher mortality rates than non-pregnant women of the same age.

 

The following anecdotal reports come from a 2008 CDC EID Journal article:

 

Rasmussen SA, Jamieson DJ, Bresee JS. Pandemic influenza and pregnant women. Emerg Infect Dis [serial on the Internet].   

 

Among 1,350 reported cases of influenza among pregnant women during the pandemic of 1918, the proportion of deaths was reported to be 27% (5).

 

Similarly, among a small case series of 86 pregnant women hospitalized in Chicago for influenza in 1918, 45% died (6).

 

Among pregnancy-associated deaths in Minnesota during the 1957 pandemic, influenza was the leading cause of death, accounting for nearly 20% of deaths associated with pregnancy during the pandemic period; half of women of reproductive age who died were pregnant (7).

 

 

Pregnant women also appear to be more susceptible to influenza than non-pregnant women, although the exact reasons for this aren't well understood.

 

It is believed, however, that the normal protections of a woman's immune system are temporarily altered to allow her to carry what is essentially a foreign body- a fetus - without rejection.

 

And that alteration can place the mother (and child) at greater risk of infection from the influenza virus.

 

Which is why the CDC and many other public health agencies strongly encourage pregnant women to get vaccinated against both seasonal and pandemic influenza. 

 

 

Very early into the 2009 H1N1 outbreak – even before the declaration of a pandemic by the World Health Organization – it became apparent that pregnant women were making up a disproportionate number of ICU admissions for influenza.

 

On May 1st of 2009, a little more than a week after the first cases of novel H1N1 began to make headlines, the CDC published new guidelines for pregnant women in the Health Care or Education field that might come in direct contact with the Swine flu virus (See CDC Guidelines On Pregnancy And Pandemic Flu).

 

Two weeks after that the MMWR published case studies of three pregnant women who had contracted novel H1N1.

 

Throughout the summer, pregnancy and flu was a major topic by public health officials around the world, with the WHO issuing a Pandemic Briefing # 5: Influenza In Pregnant Women in late July of 2009.

 

Since then, we’ve seen a number of studies on the impact of the H1N1 virus on pregnant women, including BMJ Study: Pregnancy & Flu – published in the spring of 2010.  

 

 

Although it was widely reported (see Pregnancy & Flu: A Bad Combination) during 2009 that pregnant women were up to 6 times more likely to be hospitalized with influenza than were non-pregnant women, this study found the risks of influenza death among pregnant women to be actually higher.

 

 

Less well quantified has been the health impact on the unborn child when the mother was hospitalized with H1N1 influenza.

 

Today an open access research article in the BMJ that found that pregnant women who were admitted to the hospital with an  H1N1 infection experienced a 3 to 4 times higher rate of preterm birth, 4 to 5 times greater risk of stillbirth, and a 4 to 6 times higher rate of neonatal death.

 

 

 

Perinatal outcomes after maternal 2009/H1N1 infection: national cohort study

Matthias Pierce, Jennifer J Kurinczuk, Patsy Spark, Peter Brocklehurst, Marian Knight,

Accepted 13 April 2011

Abstract

Objectives To follow up a UK national cohort of women admitted to hospital with confirmed 2009/H1N1 influenza in pregnancy in order to obtain a complete picture of pregnancy outcomes and estimate the risks of adverse fetal and infant outcomes.

 

Participants 256 women admitted to hospital with confirmed 2009/H1N1 in pregnancy during the second wave of pandemic infection between September 2009 and January 2010; 1220 pregnant women for comparison.

 

Main outcome measures Rates of stillbirth, perinatal mortality, and neonatal mortality; odds ratios for infected versus comparison women.

 

Results Perinatal mortality was higher in infants born to infected women (10 deaths among 256 infants; rate 39 (95% confidence interval 19 to 71) per 1000 total births) than in infants of uninfected women (9 deaths among 1233 infants; rate 7 (3 to 13) per 1000 total births) (P<0.001).

This was principally explained by an increase in the rate of stillbirth (27 per 1000 total births v 6 per 1000 total births; P=0.001). Infants of infected women were also more likely to be born prematurely than were infants of comparison women (adjusted odds ratio 4.0, 95% confidence interval 2.7 to 5.9).

Infected women who delivered preterm were more likely to be infected in their third trimester (P=0.046), to have been admitted to an intensive care unit (P<0.001), and to have a secondary pneumonia (P=0.001) than were those who delivered at term.

Conclusions This study suggests an increase in the risk of poor outcomes of pregnancy in women infected with 2009/H1N1, which reinforces the message from studies of maternal risk alone. The health of pregnant women is an important public health priority in future waves of this and other influenza pandemics.

 

 

 

The bottom line is that influenza presents a serious health threat to the mother, and to the child she carries.  

 

While flu vaccines are very safe, and most years reasonably effective, many pregnant women avoid taking one out of fears they may experience a rare adverse reaction.

 

Today’s study highlights the fact that when you are dealing influenza and pregnancy, simply doing nothing represents a serious health risk of its own.

Risks that could be substantially reduced by vaccination.

»» Read More

A Bad Way To Start Your Day

 

 

 

# 5545

STEMI on EKG- credit Wikidoc.org 

 

Admittedly, there is no good time to have a heart attack, but new research is casting light on the fact that the time of day when a person has a myocardial infarction may affect its severity.

 

Last November (see A Different Kind Of Holiday Tradition) I wrote about the seasonality of heart attacks (they spike as much as 33% during the holiday season - between Thanksgiving and mid-January).

 

The reasons for this are not entirely clear, but may be due to a variety of factors:

 

Colder temperatures, increased respiratory infections, over indulgence in food and alcohol, diminished activity levels, forgetting to take prescription medicines, and the combined stressors of shopping, running up debt for gifts, traveling, meal preparation, and/or the stress that comes from dysfunctional family gatherings.

 

But as any paramedic will tell you, mornings are prime time for cardiac calls anytime of the year.

 

In fact studies have shown that people are 40% more likely to experience a heart attack between 4am-10am than any other time of the day (cite). 

 

But now there is growing evidence that myocardial infarctions that occur in the morning may cause more heart muscle damage than those that occur during other times of the day as well.

 

First the study which appears in the BMJ Heart Journal, then some discussion.

 

Heart doi:10.1136/hrt.2010.212621

Circadian variations of infarct size in acute myocardial infarction

Aida Suárez-Barrientos, Pedro López-Romero, David Vivas1,Francisco Castro-Ferreira, Ivan Núñez-Gil, Eduardo Franco, Borja Ruiz-Mateos, Juan Carlos García-Rubira, Antonio Fernández-Ortiz, Carlos Macaya, Borja Ibanez

Abstract

Background The circadian clock influences a number of cardiovascular (patho)physiological processes including the incidence of acute myocardial infarction. A circadian variation in infarct size has recently been shown in rodents, but there is no clinical evidence of this finding.

 

Objective To determine the impact of time-of-day onset of ST segment elevation myocardial infarction (STEMI) on infarct size.

 

<SNIP>

 

Conclusions Significant circadian oscillations in infarct size were found in patients according to time-of-day of STEMI onset. The infarct size was found to be significantly larger with STEMI onset in the dark-to-light transition period (6:00–noon). If confirmed, these results may have a significant impact on the interpretation of clinical trials of cardioprotective strategies in STEMI.

 

 

Essentially, researchers looked at cardiac enzyme levels of more than 800 patients in Madrid, Spain who were having an STEMI (ST segment elevation myocardial infarction).

 

STEMIs are serious heart attacks that affect a large portion of cardiac muscle and show up on EKGs (ST segment elevation) and produce a spike in cardiac enzymes (indicative of muscle damage).

 

The peak levels of cardiac enzymes released - Creatine kinase (CK) and troponin-I (TnI) – provide a good indication of the amount of coronary muscle damage.

 

By comparing peak enzyme levels in patients with their time of coronary onset, researchers were able to determine what time of day the most severe heart attacks occurred. 

 

And the results  showed that heart attacks that began during the dark-to-light transition period (6:00–noon), showed roughly 20% more tissue death, compared with heart attacks with onsets between 6pm and midnight.

 

The current theory as to why this might be is that the body’s circadian rhythm influences the production of cardio-protective proteins called salvage kinases, which are released in greater quantities later in the day.

 

The hope is that this kind of research will eventually lead to new therapies and treatments which might reduce the amount of muscle damage during heart attacks.

 

For now, the best defense is to remember to take your prescribed medications and to pay attention to the signs and symptoms of a heart attack, and not delay calling 9-1-1.

 

From the CDC’s Heart Attack Information page:

Symptoms of a Heart Attack

The five major symptoms of a heart attack are—

• Pain or discomfort in the jaw, neck, or back.
• Feeling weak, light-headed, or faint.
• Chest pain or discomfort.
• Pain or discomfort in arms or shoulder.
• Shortness of breath.

If you think that you or someone you know is having a heart attack, you should call 9–1–1 immediately.

 

And while you are thinking about gifts for your family and friends this year, one gift you can give them is to take a CPR course – so you can help save their life if their heart should stop due to a heart attack, electrocution, anaphylactic reaction or drowning.

 

Compression-only CPR is now the standard for laypeople, and is easier to do than the old way.

 

While it won’t take the place of an actual class, you can watch how it is done on in this brief instructional video from the American Heart Association.

 

 

A class only takes a few hours, and it could end up helping you save the life of someone you love.

 

To find a local CPR course contact your local chapter of the American Red Cross, the American Heart Association, or (usually) your local fire department or EMS can steer you to a class.

»» Read More

Statins & Pneumonia: Revisited

 

# 5465

 

 

The idea certainly isn’t new.  

 

If fact, I mentioned it in this blog as far back as 2006, and have written about it extensively probably a dozen times since then.  

 

While unproven, and not without controversy, over the years we’ve seen several studies suggesting that taking statins - cholesterol reducing drugs - can improve survival rates among those with influenza and/or pneumonia.

 

Dr. David Fedson – former Professor of Medicine at the University of Virginia School of Medicine and formerly Director of Medical Affairs, Aventis Pasteur MSD - has long championed the idea that we should be looking at statins for pandemic flu, which he believes may help modulate the immune response.

 

A couple of his papers on the subject include:

 

Pandemic Influenza: A Potential Role for Statins in Treatment and Prophylaxis

David S. Fedson^a

 

New Approaches to Confronting an Imminent Influenza Pandemic

Dr. Fedson and Peter Dunnill, DSc,FREng

 

 

In 2007 we saw a study that seemed to support the idea, one that indicated that statins lowered the mortality rate of people with pneumonia.

 

 

Statin drugs lower respiratory death risk: study

Tue Apr 10, 2007 12:40pm EDT

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - People who use statin drugs are less likely to die of influenza and chronic bronchitis, according to a study that shows yet another unexpected benefit of the cholesterol-lowering medications.

 

And in 2008 this encouraging report made the headlines:

 

Statins may cut pneumonia death, blood clot risks

27 Oct 2008 20:00:13 GMT

Source: Reuters

By Will Dunham

WASHINGTON, Oct 27 (Reuters) - Cholesterol-fighting drugs known as statins reduced the risk of dying from pneumonia or developing dangerous blood clots in the legs, adding to a growing list of benefits from the popular drugs, two research groups said on Monday.

 

 

But not all of the studies have been positive.

 

In July of 2009 there was a report that found no evidence of benefit among pneumonia patients (see Another Take On Statins And Pneumonia) taking statins.

 

 

But another study, presented in October of 2009 at the annual meeting of the IDSA, the Infectious Diseases Society of America, in Philadelphia suggested the opposite - that statins cut the mortality rate for seasonal flu by 50%.

 

Maryn McKenna writing for CIDRAP brought us the details.

 

Statins may help patients with severe seasonal flu

Maryn McKenna Contributing Writer

Oct 29, 2009 (CIDRAP News) – Commonly available drugs that are sold in lower-cost generic versions improve the survival of patients hospitalized for seasonal influenza, researchers reported today, raising the possibility of a widely available treatment that could be used in a severe flu pandemic if other drugs are in short supply.

 

 

So while not all of these studies are in agreement, many of them have supported the notion that statins may be of considerable value during a pandemic, and may contribute to the survival rate of patients with pneumonia.

 

 

Today we’ve another study – this time by the London School of Hygiene and Tropical Medicine published in the BMJ – that looks at 6 month post-pneumonia survival rates among those taking statins, and those not taking these medications.

 

While there may be other factors at work here – and more research is needed - survival rates were considerably higher (87% vs 80%) among those already taking statins when they fell ill.

 

As of this posting, the study has not appeared on the BMJ website.  I assume it will shortly. 

 

Here are excerpts from the LSHTM press release:

 

 

Pneumonia death rate lower among people who take statins

Tuesday, 5 April 2011

LSHTM study finds evidence for protective effect of cholesterol-lowering medication

 

Taking statins could help prevent people dying from pneumonia, according to a study by the London School of Hygiene and Tropical Medicine.

 

The researchers found that the risk of death in the six month period after diagnosis of pneumonia was substantially lower among those who were already receiving the cholesterol-lowering drugs compared with those who were not.

 

Previous studies have suggested that statins may be associated with a more favourable outcome after bacterial infection.

 

This study, published online in the BMJ today, supports a possible protective effect of statins against mortality in patients with pneumonia.

 

But the researchers point out that as they looked at patients who were already taking the medication when they developed pneumonia, a randomised clinical trial is needed to determine whether starting a statin at the time of diagnosis has a similar effect.

(CONTINUE  . . . . )

Notes to Editors:

Title of study online at BMJ: “Effect of statin treatment on short term mortality after pneumonia episode: cohort study” by Ian Douglas, Stephen Evans and Liam Smeeth.

 

 

The $64 question is whether administering statins after a pneumonia diagnosis provides any protective benefits.  There are reasons to believe that it might, but further studies are needed to prove or disprove it.

 

If you’d like to learn more about Dr. David Fedson and some of his ideas on statins, there are three 1-hour radio interviews available from 2009 that were conducted by Sharon Sanders of FluTrackers. 

 

You’ll find them archived at the FluTrackers links below.

 

David Fedson 06 April 2009

http://www.flutrackers.com/forum/aud...pril062009.mp3

David Fedson 18 May 2009

http://www.flutrackers.com/forum/aud...May18.2009.mp3

David Fedson 02 November 2009

http://www.flutrackers.com/forum/aud...Nov02.2009.mp3

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BMJ: Effectiveness of AS03 adjuvanted pandemic H1N1 vaccine

 

 

 

# 5287

 

We’ve another study – this time from the BMJ – that indicates that the 2009 H1N1 AS03 adjuvanted vaccine – used in Canada and much of Europe - was very effective in preventing the pandemic flu.

 

Researchers looked at 552 patients consulting their GP’s between Nov 8th and Dec. 5th, 2009 across 4 Canadian provinces and found that the H1N1 virus was detected in 209 of them.  

 

Of those, 2 (1%) had received the pandemic jab at least two weeks earlier, while 58 (17%) patients who had received the shot tested negative.

 

The researchers found the vaccine to be 93% effective, at least in recipients under the age of 50.

 

Only 20% of those in the study were over the age of 50, and so further research on the vaccine’s effectiveness in that age group is needed.

 

First the abstract, then I’ll return with a little more.

 

 

• BMJ 2011; 2011; 342:c7297

Effectiveness of AS03 adjuvanted pandemic H1N1 vaccine: case-control evaluation based on sentinel surveillance system in Canada, autumn 2009

Danuta M Skowronski, Naveed Z Janjua, Gaston De Serres, Travis S Hottes, James A Dickinson, Natasha Crowcroft, Trijntje L Kwindt, Patrick Tang, Hugues Charest, Kevin Fonseca, Jonathan B Gubbay, Nathalie Bastien, Yan Li, Martin Petric, clinical virologist

Accepted 22 November 2010

Abstract

Objective To assess the effectiveness of the pandemic influenza A/H1N1 vaccine used in Canada during autumn 2009.

 

Design Test negative incident case-control study based on sentinel physician surveillance system.

 

Setting Community based clinics contributing to sentinel networks in British Columbia, Alberta, Ontario, and Quebec, Canada.

 

Participants 552 patients who presented to a sentinel site within seven days of onset of influenza-like illness during the primary analysis period between 8 November and 5 December 2009; participants were mostly (>80%) children and adults under 50 years old.

 

Interventions Monovalent AS03 adjuvanted pandemic influenza A/H1N1 vaccine as the predominant formulation (>95%) distributed in Canada.

 

Main outcome measures Vaccine effectiveness calculated as 1−(odds ratio for influenza in vaccinated (received pandemic H1N1 vaccine at least two weeks before onset of influenza-like illness) versus unvaccinated participants), with adjustment for age, comorbidity, province, timeliness of specimen collection, and week of illness onset. Sensitivity analyses explored the influence of varying analysis periods between 1 November and 31 December, receipt of trivalent seasonal influenza vaccine, and restriction to participants without comorbidity.

 

Results During the primary analysis period, pandemic H1N1 was detected by reverse transcription polymerase chain reaction in 209/552 (38%) participants; rates were highest in children and young adults (40%) and lowest in people aged 65 or over (9%). Among the 209 cases, 35 (17%) reported comorbidity compared with 80/343 (23%) controls. Two (1%) cases had received pandemic H1N1 vaccine at least two weeks before the onset of illness, compared with 58/343 (17%) controls, all single dose. Adjusted vaccine effectiveness overall was 93% (95% confidence interval 69% to 98%). High estimates of vaccine protection—generally at least 90%—were maintained across most sensitivity analyses.

 

Conclusions Although limited by a small number of vaccine failures, this study suggests that the monovalent AS03 adjuvanted vaccine used in Canada during autumn 2009 was highly effective in preventing medically attended, laboratory confirmed pandemic H1N1 illness, with reference in particular to a single dose in children and young adults.

 

 

While limited by its relatively small size, this study adds to the weight of evidence showing that the 2009 pandemic vaccine was very effective in preventing the flu.

 

Last month we saw two studies released showing that the unadjuvanted vaccine provided an adjusted vaccine effectiveness for adults under 65 of about 72%.

Eurosurveillance: Another Pandemic Vaccine Effectiveness Study

PLoS Medicine: Effectiveness Of The 2009 Pandemic Vaccine

 

In May of 2010 we saw a comparison study (see BMJ: Immunogenicity Of Adjuvanted vs. Unadjuvanted H1N1 Vaccines) between GSK’s Pandemrix, containing the adjuvant AS03, verses Baxter’s unadjuvanted Celvapan in British children.

 

Although the adjuvanted Pandemrix vaccine was associated with a higher rate of (usually mild) side effects (fever, injection site soreness), it produced a superior immune response.  

 

While there remain some open questions regarding the  Pandemrix vaccine and reports of narcolepsy in adolescents and children in some Scandinavian countries, except for a handful of suspected adverse events under investigation, the safety profile of the adjuvanted vaccine has been excellent.

 

Lancet: Immunogenicity and safety Of Adjuvanted Flu Vaccines

 

While admittedly not 100% perfect, the adjuvanted and unadjuvanted 2009 H1N1 pandemic vaccines have proven themselves to have been very safe, and very effective.

 

Given the short time in which scientists, manufacturers, and public health agencies had to identify, isolate, grow, test, and distribute a pandemic vaccine - despite some bumps along the way – it is hard not to view this emergency vaccination program as a remarkable success.

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BMJ: Oxygen Delivery and COPD

 

 

# 4992

 

 

At the risk of blogging on a subject a little too `inside baseball’, a study caught my eye this morning in the BMJ on the survival rates of COPD (Chronic Obstructive Pulmonary Disease) patients treated by paramedics with either high concentrations or low concentrations of oxygen.

 

This has been a contentious subject in the medical community for a long time.

 

I was taught – back in the stone age of emergency medicine (early 1970s) – not to give more than 2 liters of oxygen to a COPD patient (we didn’t have pulse-ox meters onboard back then).

 

Oxygen, as my paramedic instructor often said, was a drug.  And too much O2 for patients with COPD could result in respiratory failure.

 

For many years, however, it has been standard protocol for a lot of EMS services not to deprive COPD patients in serious respiratory distress high flow rates of oxygen.

 

Running contrary to that opinion, in 2008 the British Thoracic Society came up with guidelines that restricted in-the-field oxygen delivery for COPD patients – and those were adopted by British Ambulance services in 2009.

 

The guideline recommends that oxygen is administered to patients whose oxygen saturation falls below the target saturation ranges (94-98% for most acutely ill patients and 88-92% for those at risk of type 2 respiratory failure with raised carbon dioxide level in the blood), and that those who administer oxygen therapy should monitor the patient and keep within those specified target saturation ranges. 

 

But elsewhere in the world, delivery of high flow rates of oxygen for COPD patients (both pre-hospital and in-hospital) remains common.

 

This new study (BMJ 2010; 341:c5462), which appeared in yesterday’s British Medical Journal as an open access research article, may shake up that practice.

It has relevance for emergency responders, and for those who have in-home oxygen setups for someone with COPD (primarily Emphysema).

 

Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trial

1. Michael A Austin,Karen E Wills, Leigh Blizzard, Eugene H Walters, Richard Wood-Baker

Accepted 19 August 2010

Abstract

Objectives To compare standard high flow oxygen treatment with titrated oxygen treatment for patients with an acute exacerbation of chronic obstructive pulmonary disease in the prehospital setting.

Design Cluster randomised controlled parallel group trial.

Setting Ambulance service in Hobart, Tasmania, Australia.

Participants 405 patients with a presumed acute exacerbation of chronic obstructive pulmonary disease who were treated by paramedics, transported, and admitted to the Royal Hobart Hospital during the trial period; 214 had a diagnosis of chronic obstructive pulmonary disease confirmed by lung function tests in the previous five years.

Interventions High flow oxygen treatment compared with titrated oxygen treatment in the prehospital (ambulance/paramedic) setting.

Main outcome measure Prehospital or in-hospital mortality.

 

The results?  Again from the abstract:

 

 

Titrated oxygen treatment reduced mortality compared with high flow oxygen by 58% for all patients (relative risk 0.42, 95% confidence interval 0.20 to 0.89; P=0.02) and by 78% for the patients with confirmed chronic obstructive pulmonary disease (0.22, 0.05 to 0.91; P=0.04).

 

Patients with chronic obstructive pulmonary disease who received titrated oxygen according to the protocol were significantly less likely to have respiratory acidosis (mean difference in pH 0.12 (SE 0.05); P=0.01; n=28) or hypercapnia (mean difference in arterial carbon dioxide pressure −33.6 (16.3) mm Hg; P=0.02; n=29) than were patients who received high flow oxygen.

 

 

Remarkable numbers, assuming that future studies corroborate the results.  

There were limitations to this study, including a failure to obtain arterial blood gases for many of the patients within 30 minutes of their arrival at the ER, and a lack of  in-hospital monitoring of treatment.

Breaches in protocol were apparently common during this study, with more oxygen being administered in some cases than specified by the study.

 

And of course, this study was limited in size as well. 

 

Which means that the controversy over which protocol to use isn’t resolved.

 

It is, after all,  counter-intuitive to deprive someone who is in serious respiratory distress abundant oxygen. And so more studies will certainly be needed before titering oxygen rates for COPD patients gains wide acceptance.

 

Amazing, though, that what we believed back in the early 1970s – and what was subsequently discarded - may end up coming back as the standard today.

 

 

The authors write:

 

Conclusions and policy implications

This randomised controlled trial found that titrated oxygen treatment in the prehospital setting resulted in a 78% reduction in the risk of in-hospital respiratory failure and subsequent mortality, compared with high flow oxygen treatment, and a decreased risk of hypercapnia and respiratory acidosis for patients with an acute exacerbation of chronic obstructive pulmonary disease.

 

Our findings provide the first high quality evidence from a randomised controlled trial for the development of universal guidelines and support the British Thoracic Society’s recent guidelines on acute oxygen treatment, which recommend that oxygen should be administered only at concentrations sufficient to maintain adequate oxygen saturations.

 

Although our findings may need to be confirmed in larger studies across other health systems, implementation of the new guidelines will now be easier. However, resources for an aggressive campaign of education will still be needed to change the “more is better” oxygen culture that may ignore the potential dangers of hyperoxia.

 

 

 What is already known on this topic

• Audits have shown increased mortality, acidosis, and hypercarbia in patients with acute exacerbations of chronic obstructive pulmonary disease treated with high flow oxygen

• High flow oxygen is still used routinely in prehospital and hospital areas for breathless patients with chronic obstructive pulmonary disease

• A “more is better” oxygen culture is strong in prehospital management

What this study adds

• Titrated oxygen treatment reduces mortality, acidosis, and hypercarbia in patients with acute exacerbation of chronic obstructive pulmonary disease treated before arrival at hospital

• The risk of death was reduced by 78% by use of titrated oxygen rather than high flow oxygen, with a number needed to harm of 14

• These findings provide strong evidence that titrated oxygen treatment should be used for hypoxic or breathless patients with chronic obstructive pulmonary disease in prehospital settings

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BMJ: Efficacy of Oseltamivir In Mild H1N1

 

 

# 4948

 

 

One of the ongoing debates in the world of influenza has been over the efficacy of administering oseltamivir (Tamiflu) in the treatment of mild influenza in otherwise healthy individuals.

 

You may recall that last December a cluster of articles appeared in the BMJ which seriously questioned the lack of supportive scientific evidence in this matter (see BMJ: A Review Of Tamiflu’s Efficacy Against Seasonal Influenza).

 

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 was 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, the authors stated that more studies were needed.

 

Although it certainly won’t end the debate, we’ve a new open access retrospective study appearing this week in the BMJ  which suggests that administration of oseltamivir may have significantly reduced the incidence of pneumonia among otherwise healthy pandemic H1N1 patients.

 

BMJ 2010; 341:c4779 doi: 10.1136/bmj.c4779 (Published 28 September 2010)

Cite this as: BMJ 2010; 341:c4779

• Research

Effectiveness of oseltamivir on disease progression and viral RNA shedding in patients with mild pandemic 2009 influenza A H1N1: opportunistic retrospective study of medical charts in China

 

Hongjie Yu, Qiaohong Liao,Yuan Yuan,Lei Zhou, Nijuan Xiang, Yang Huai, Xiuhua Guo, Yingdong Zheng, H Rogier van Doorn, Jeremy Farrar, Zhancheng Gao, Zijian Feng, Yu Wang, Weizhong Yang

Conclusions Chinese patients with 2009 H1N1 infection predominantly presented with features of uncomplicated, self limiting acute respiratory illness. 2009 H1N1 might be shed longer than seasonal influenza virus.

Treatment with oseltamivir was associated with a significantly reduced development of radiographically confirmed pneumonia and a shorter duration of fever and viral RNA shedding.

Though these patients benefited from treatment, the findings should be interpreted with caution as the study was retrospective and not all patients underwent chest radiography.

 

 

For those who would like the short version, there is a press release covering the highlights.  I’ve excerpted a few paragraphs.  Follow the link to read it in its entirety.

 

Swine flu patients benefited from taking Tamiflu, says study

Research: Effectiveness of oseltamivir on disease progression and viral RNA shedding in patients with mild pandemic 2009 influenza A H1N1: opportunistic retrospective study of medical charts in China

Healthy people who caught swine flu during the 2009 pandemic may have been protected against developing radiographically (x-ray) confirmed pneumonia by taking the antiviral drug oseltamivir (Tamiflu), concludes a study of cases in China published on bmj.com today.

 

The researchers also show that oseltamivir treatment was associated with shorter duration of fever and viral RNA shedding (the period when a virus is contagious), although they stress that their findings should be interpreted with caution.

(Continue . . .)

 

While the  lack of peer-reviewed RCTs (Randomized Controlled Trials) on oseltamivir – which can provide genuine ethical dilemmas to mount – will continue to leave some questioning the efficacy of Tamiflu in mild influenza, anecdotal reports and retrospective analysis continues to show the drug to be beneficial, particularly in cases of severe influenza.

 

Today’s study adds a new dimension to the debate, by strongly suggesting that it may reduce morbidity in healthy adults with mild influenza symptoms.

 

Additionally, the researchers reported that:

 

Our study suggests that 2009 H1N1 is shed from one day before the onset of symptoms to eight days after onset for most (91%) patients and can be shed up to 21 days.

The BMJ’s summary reads, in part:

 

What this study adds

• In patients with mild pandemic 2009 H1N1 infection, oseltamivir can protect against subsequent development of radiographic pneumonia, even in those who start treatment more than two days after the onset of symptoms

• Early oseltamivir treatment within two days of symptom onset can reduce the duration of fever and viral RNA shedding

• Pandemic 2009 H1N1 virus is shed from one day before the onset of clinical symptoms to up to eight days after onset for most patients and is shed for longer than seasonal influenza virus

 

There are other concerns when it comes to the routine use of oseltamivir with mild influenza, including the possibility of causing side effects and the (potential, at least) of generating resistant strains of the influenza virus.

 

Both matters to be taken up by other studies and on another day.

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