Study: The Effects Of School Closures During A Pandemic

 

 

 

# 6125

 

 

Although not without its critics, extended school closures have been promoted as one of a list of NPIs (non pharmaceutical interventions) that might be used to slow the spread of illness during a severe influenza pandemic.

 

 

The chart above, taken from the PNAS journal article entitled Public Health Interventions and Pandemic Intensity During the 1918 Influenza Pandemic, shows the excess mortality in two American cities. The tall spike represents Philadelphia, while the lower curve represents St. Louis.

 

Many researchers believe the startling difference in attack rates, and mortality, in these two cities can be explained by the way each city dealt with the outbreak.

 

In St. Louis, the Health Department closed public venues such as schools, theatres and churches very early in the outbreak, while Philadelphia did not.

 

During the spring of 2009, when novel H1N1 first began to spread, schools closures were recommended by the CDC, and by other public health entities around the world.

 

By early May it became apparent that the severity of this particular influenza virus was less than originally feared, and many public health agencies moderated their recommendations (see CDC No Longer Recommending School Closures For A/H1N1).

 

Some school districts, in the U.S., and elsewhere around the world, continued to close schools on a case-by-case basis well into the fall of 2009.

 

School closings are controversial and they do not come without some social and economic costs (see The Debate Over School Closures).

 

Critics point out that working parents rely on schools to watch their kids for much of the year during the day, and many low income families benefit from the school lunch program.

 

And of course, when schools are closed during a pandemic, some kids may congregate elsewhere and spread the virus anyway.

 

While decisions on whether to close schools during a pandemic might well be trumped by parental concerns, it is important for policymakers to get some idea of the benefits that proactive school closings would generate. 

 

To that end we’ve seen a number of studies that came out of the most recent pandemic, and while the results have not all been in alignment, many have indicated substantial benefit from school closures.

 

In a report that appeared last year in the journal Eurosurveillance (see Eurosurveillance: New Research On Pandemic Influenza), we saw several studies that attempted to quantify the benefits of school closures:

 

• Three studies out of Japan found a beneficial effect during the 2009 pandemic by using antiviral drugs and/or school closure (of varying length and timing) to interrupt its transmission.

• Conversely, a fourth study suggested that early school closures could have adversely affected herd immunity in the school environment, with lower cumulative infection rates in schools that delayed closure.

 

Last May (see NIH: School Closings Effective In 2009 Pandemic) we saw a report indicating that school closings in Mexico reduced disease transmission by as much as 37%.

 

This from the NIH.

 

Tuesday, May 24, 2011
5 p.m. EDT

Mexican flu pandemic study supports social distancing

Fogarty research published in PLoS Medicine

Eighteen-day periods of mandatory school closures and other social distancing measures were associated with a 29 to 37 percent reduction in influenza transmission rates in Mexico during the 2009 pandemic. The research was carried out by scientists at the Fogarty International Center at the National Institutes of Health and published in PLoS Medicine.

 

(Continue . . .)

 

I’ve posted on a number of other studies of the effects of school closures over the past few years, including:

 

Study: Pandemic Mitigation by Early School Closure

Study: Student Behavior During Pandemic School Closings

School Closures Revisited

 

All of which serves as prelude and introduction for a new study, just out in the Annals of Internal Medicine, that looks at the effects of school closures in Canada during the 2009 pandemic.

 

Effects of School Closure on Incidence of Pandemic Influenza in Alberta, Canada

David J.D. Earn, PhD; Daihai He, PhD; Mark B. Loeb, MD, MSc; Kevin Fonseca, PhD; Bonita E. Lee, MD, MSc; and Jonathan Dushoff, PhD

Abstract (excerpts)

Background: Control of pandemic influenza by social-distancing measures, such as school closures, is a controversial aspect of pandemic planning. However, investigations of the extent to which these measures actually affect the progression of a pandemic have been limited.

 

<SNIP>

 

Results: The ending and restarting of school terms had a major effect in attenuating the first wave and starting the second wave of pandemic influenza cases. Mathematical models suggested that school closure reduced transmission among school-age children by more than 50% and that this was a key factor in interrupting transmission. The models also indicated that seasonal changes in weather had a significant effect on the temporal pattern of the epidemic.

 

<SNIP>

 

Conclusion: Analysis of data from unrestricted virologic testing during an influenza pandemic provides compelling evidence that closing schools can have dramatic effects on transmission of pandemic influenza. School closure seems to be an effective strategy for slowing the spread of pandemic influenza in countries with social contact networks similar to those in Canada.

 

While the entire article is behind a pay wall, for more on this we can go to the press release from McMaster University.

 

School closures slow spread of pH1N1

Should be considered as a control measure during pandemic outbreaks

Hamilton, ON (Feb. 6, 2012) - Closing elementary and secondary schools can help slow the spread of infectious disease and should be considered as a control measure during pandemic outbreaks, according to a McMaster University led study.

 

Using high-quality data about the incidence of influenza infections in Alberta during the 2009 H1N1 flu pandemic, the researchers show that when schools closed for the summer, the transmission of infection from person to person was sharply reduced.

 

"Our study demonstrates that school-age children were important drivers of pH1N1 transmission in 2009," says David Earn, lead author of the study published in Annals of Internal Medicine. Earn is professor in the Department of Mathematics and Statistics and member of McMaster's Michael G. DeGroote Institute for Infectious Disease Research (IIDR).

 

Alberta was the only Canadian province to continue extensive virologic testing throughout the first wave and continuously to the middle of the second wave of the 2009 pandemic, allowing researchers to identify the causes of changes in incidence as the pandemic progressed.

"The data that we obtained were so good that our plots immediately revealed a huge drop in incidence when schools were closed for the summer," says Earn. "Using state-of-the-art modeling, we then demonstrated that transmission was reduced by at least 50 per cent."

(Continue . . . )

 

 

Although the severity of any novel pandemic virus will no doubt figure into the equation (as will the social and economic costs of shuttering schools), today’s study adds considerable weight to the notion that school closures could be an effective intervention during the next influenza pandemic.

»» Read More

Our First Line Of Defense

 

Photo Credit PHIL (Public Health Image Library)

 

 

# 5992

 

One of the concepts well illustrated during the initial outbreak of the H1N1 `swine flu virus’ in 2009 was that – until a vaccine could be developed, produced, and deployed – our only real defenses against any emerging infectious disease are NPIs; non pharmaceutical interventions.

 

Which is why flu hygiene (covering coughs/sneezes, disposing of tissues, washing hands often, and staying home when sick) was heavily promoted to the public during the pandemic.

 

Healthcare settings, where large numbers of vulnerable people are gathered in close proximity, are also the place that those infected with a new virus are likely to show up first.

 

Making the use of NPIs all the more important, to protect not only the staff, but other patients as well.

 

This morning we’ve a couple of studies that look at attitudes towards, and actually implementation of, NPIs and basic infection control procedures by both medical students and healthcare providers.

 

The most basic of NPIs is handwashing, and despite it having been more than 160 years since Ignaz Semmelweis published his work on the importance of hand hygiene, compliance rates in healthcare settings remain disturbingly low.

 

This is a subject we’ve visited many times before, including:

 

Giving Germs A Helping Hand 

Hand Hygiene Among Doctors Exposed

A Movement With Five Moments

Despite increased awareness and concern over HAIs (Hospital Acquired Infections), global handwashing campaigns, and the proliferation of hand sanitizing dispensers there remain serious gaps in this most basic infection control practice.

 

In the American Journal of Infection Control we’ve a study that surveyed beliefs of 1st year medical students over when it was appropriate to wash you hands when interacting with a patient.

Beliefs about hand hygiene: A survey in medical students in their first clinical year

Karolin Graf, MD, Iris F. Chaberny, MD, Ralf-Peter Vonberg, MD

Medical students were asked regarding knowledge and beliefs on hand hygiene before entering the clinical phase of education. By this, we noticed a lack of knowledge concerning the correct indications for hand disinfection. Regardless of previous experience in hospitals, the medical students expected that the compliance towards hand hygiene would be worse in more experienced physicians and senior consultants—who are often considered to be role models for medical students.

 

While this study is behind a pay wall, we do get additional details from a press release from Elsevier Health Services.

 

Elsevier Health Sciences

2 out of 3 medical students do not know when to wash their hands

Washington, DC, December 1, 2011 -- Only 21 percent of surveyed medical students could identify five true and two false indications of when and when not to wash their hands in the clinical setting, according to a study published in the December issue of the American Journal of Infection Control, the official publication of APIC - the Association for Professionals in Infection Control and Epidemiology.

 

Three researchers from the Institute for Medical Microbiology and Hospital Epidemiology at Hannover Medical School in Hannover, Germany collected surveys from 85 medical students in their third year of study during a lecture class that all students must pass before bedside training and contact with patients commences. Students were given seven scenarios, of which five ("before contact to a patient," "before preparation of intravenous fluids," "after removal of gloves," "after contact to the patient's bed," and "after contact to vomit") were correct hand hygiene (HH) indications. Only 33 percent of the students correctly identified all five true indications, and only 21 percent correctly identified all true and false indications.

(Continue . . . )

 

 

The next stop is a study that appears in the SHEA journal Infection Control and Hospital Epidemiology that shows that the inadequate use of masks by healthcare workers during the opening days of the 2009 pandemic put them at greater risk of contracting the virus.

 

 

Transmission of 2009 Pandemic Influenza A (H1N1) Virus among Healthcare Personnel-Southern California, 2009.

Jaeger JL, Patel M, Dharan N, Hancock K, Meites E, Mattson C, Gladden M, Sugerman D, Doshi S, Blau D, Harriman K, Whaley M, Sun H, Ginsberg M, Kao AS, Kriner P, Lindstrom S, Jain S, Katz J, Finelli L, Olsen SJ, Kallen AJ.

Source

Epidemic Intelligence Service, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia.

We’ve a press release from SHEA with the details.

 

Study finds inadequate mask use among health care workers early in 2009 H1N1 outbreak

Inadequate use of masks or respirators put health care workers at risk of 2009 H1N1 infection during the earliest stages of the 2009 pandemic in the U.S., according to a study published in the December issue of Infection Control and Hospital Epidemiology, the journal of the Society of Healthcare Epidemiology of America.

 

The study, led by the Centers for Disease Control and Prevention (CDC), tracked 63 Southern California health care workers who had contact with six of the first eight laboratory-confirmed 2009 H1N1 cases in the U.S. Because these contacts happened before the 2009 H1N1 outbreak had been widely reported, the cases shed light on how well health care workers protect themselves before a direct epidemiological threat becomes evident.

 

The investigation found that 9 of the health care workers tracked became infected with the 2009 H1N1 virus, likely from contact with infected patients. Twenty of the 63 health care workers reported that they had worn a mask or respirator at least once when in contact with patients, and no one from that group became infected with 2009 H1N1. Meanwhile, 43 workers reported never using a mask around patients, and all 9 infections occurred in workers from this group.

 

Overall, mask and respirator use was disappointingly low, the researchers report. Only 19 percent reported using a mask during every patient encounter. Use was especially low among outpatient workers, who also made up the majority of those who became infected with 2009 H1N1.

 

"The findings highlight the challenge of getting health care personnel to routinely wear Personal Protective Equipment," Jenifer Jaeger, MD, MPH, Associate Pediatrician, Massachusetts General Hospital, said. "The study also suggests that greater attention to infection control and preparedness, particularly among outpatient workers, is needed."

 

 

The irony here is that once the threat of a new viral threat became apparent, there were difficulties in providing enough PPEs (Personal Protective Equipment) - including masks and respirators - to healthcare workers in some parts of the country.

 

In June of 2009  the CDC’s MMWR (Morbidity and Mortality Weekly Report) (Volume 58, No. 23) reported hospitals weren’t doing enough to identify potential influenza cases, to isolate them, and to protect their staff (see HCPs At Risk).

 

A month later the California Nurses Association/ National Nurses Organizing Committee (CNA/NNOC) filed a complaint against one hospital, which I reported on in California Nurses Association Statement On Lack Of PPE and Report: Nurses File Complaint Over Lack Of PPE.

 

In August 2009 I reported on Nurses Protest Lack Of PPE’s in San Francisco.  And in October, I wrote CNA/NNOC Plan Protest Over Inadequate H1N1 Protection.

 

And to this, we must also add the ongoing debate over what constitutes adequate PPE protection.

 

Ideally, the well-protected HCW (Health Care Worker) working in an infectious environment would be wearing an N95 respirator, gloves, gown and eye protection.

 

 

But during the opening months of the 2009 pandemic, it became obvious that our world faced a shortage of N95 respirators, and so strategies were adopted to maximize their use.

 

In some cases nurses were issued only one N95 mask to be used for an entire 8 hour shift, and told to don it only when in direct contact with a potentially infected patient.

 

In other venues, HCWs were issued surgical masks in lieu of N95s, despite the recommendation at the time from the CDC that N95 masks were the preferred level of protection.

 

Over the past two years we’ve seen dueling studies that alternately show surgical masks to be a reasonable protective barrier against respiratory viruses  . . . or pretty much useless.

 

Take your pick.

 

Which is why last January the IOM (Institute of Medicine) released, through the National Academies Press, an extensive, 200+ page update on the use of PPEs  that essentially calls for better science on which to base our decisions regarding the right kind of protection for HCWs.

 

We were very lucky that the 2009 pandemic virus wasn’t any more transmissible, or virulent, than it turned out to be. 

 

While instilling good infection control practices is imperative in normal times, the less talked about side to this story is that during a serious global pandemic threat sometime in the future, providing adequate PPEs to healthcare workers may prove to be a major challenge.

»» Read More

Study: Flu Hygiene Reduces Respiratory Infections In School Setting

 

 

# 5980

 

 

We’ve another study that – despite returning somewhat mixed results – once again suggests the importance of maintaining good `flu hygiene’ during cold & flu season.

 

During the 2007-2008 flu season 10 Pittsburg elementary schools (grades K- 5) took part in a study where half of the schools served as controls, and half (5) were selected as `intervention’ schools.

 

Children in the intervention schools watched a special video on flu prevention, and were introduced to the `WHACK the Flu’ concepts.

 

WHACK stood for:

 

(W)ash or sanitize your hands often;

(H)ome is where you stay when you are sick;

(A)void touching your eyes, nose, and mouth;

(C)over your coughs and sneezes; and

(K)eep your distance from sick people.

 

This message was reinforced continually over the study period, and hand sanitizer dispensers were installed in each classroom and in major common areas of the intervention schools.

 

The goal was to encourage a minimum of 4 uses a day; upon arrival, before and after lunch, and prior to departure. Students were also encouraged to wash their hands and/or use the hand sanitizer as needed during the day.

 

Teachers were surveyed during the year regarding compliance rates among the students. Parents of students who were absent for more than one day received a phone call, and those who reported their child to have an ILI (influenza-like-Illness) received a home health visit where nasal swabs were obtained and tested for both influenza A & B.

 

The bottom line: at the intervention schools total student absences were reduced by 26% and lab confirmed influenza A infections were reduced by 52%.

 

Curiously, rates of influenza B were not reduced in this study, although the reasons why are less than clear.  In their discussion, the authors suggest several possible reasons, including:

 

The observation of no effect on influenza B could be attributed to differences in the basic biology and epidemiology of influenza B compared with A or to the fact that influenza B infections occurred late in the season, after compliance with the intervention possibly had waned.

 

A quick Google search returned a pdf of the full study online at this link.

 

Below you’ll find some excerpts from the abstract which may be read at the following link:

 

Pediatr Infect Dis J. 2011 Nov;30(11):921-6.

Reduction in the incidence of influenza A but not influenza B associated with use of hand sanitizer and cough hygiene in schools: a randomized controlled trial.

Stebbins S, Cummings DA, Stark JH, Vukotich C, Mitruka K, Thompson W, Rinaldo C, Roth L, Wagner M, Wisniewski SR, Dato V, Eng H, Burke DS.

(EXCERPT)

RESULTS:

A total of 3360 children participated in this study. Using reverse-transcriptase polymerase chain reaction, 54 cases of influenza A and 50 cases of influenza B were detected. We found no significant effect of the intervention on the primary study outcome of all laboratory-confirmed influenza cases (incidence rate ratio [IRR]: 0.81; 95% confidence interval [CI]: 0.54, 1.23). However, we did find statistically significant differences in protocol-specified ancillary outcomes.

Children in intervention schools had significantly fewer laboratory-confirmed influenza A infections than children in control schools, with an adjusted IRR of 0.48 (95% CI: 0.26, 0.87). Total absent episodes were also significantly lower among the intervention group than among the control group; adjusted IRR 0.74 (95% CI: 0.56, 0.97).

CONCLUSIONS:

NPIs (respiratory hygiene education and the regular use of hand sanitizer) did not reduce total laboratory-confirmed influenza. However, the interventions did reduce school total absence episodes by 26% and laboratory-confirmed influenza A infections by 52%. Our results suggest that NPIs can be an important adjunct to influenza vaccination programs to reduce the number of influenza A infections among children.

In the full paper, the authors conclude:

 

This study demonstrated that a set of NPIs can be implemented successfully on a large scale within urban schools to reduce absenteeism and the incidence of influenza A.

 

Furthermore, the results provide support for currently recommended respiratory hygiene behaviors during seasonal and pandemic influenza outbreaks and should be included as part of an overall prevention strategy to reduce the burden of influenza among school-aged children.

 

 

While useful interventions during any flu season, these techniques are even more important during an outbreak of a novel virus – such as we saw in 2009.  

 

Since vaccines typically take months to develop and even longer to deploy, simple, easy to implement NPIs (Non-pharmaceutical Interventions) such as these – while not a panacea - will undoubtedly form an important part of our initial response to any influenza epidemic.

»» Read More

JHU: Drills Expose Gaps In Infection Protection

 

 

 

# 4557

 

 

During the weeks that immediately followed the emergence of the novel H1N1 virus, not much was known about its virulence.  Schools where cases emerged were closed as a precaution, and many hospitals attempted to identify and quarantine suspect cases.

 

One of the big topics a year ago was the protection of those on the frontlines; healthcare and emergency workers.   They were considered to be the most likely to be exposed, and were in a unique position to pass the virus on to others.

 

In this article from the Johns Hopkins Gazette, we learn of lapses in infection protection protocol during 11 drills conducted at the Johns Hopkins Children’s Center last May.  The scenario involved a pediatric patient – suspected of having H1N1 – going into cardiac arrest.

 

Of the 84 HCWs who participated in these drills, 33% failed to don eye protection, 15% didn’t stop to put on a gown, and 19% did not wear a specialized respirator (presumably N95) mask.

 

The results of these mock drills were presented to the Pediatric Academic Societies meeting last week.

 

They highlight the importance of having PPEs (Personal Protective Equipment) in easy reach on hospital floors, and having a designated `gatekeeper’ whose job it is to ensure that all HCWs are compliant with infection protection protocol before entering a patient’s room.

 

This from the JHU Gazette.

 

 

H1N1 drills expose gaps in hospital infection protection

May 10, 2010
By Katerina Pesheva
Johns Hopkins Medicine

 

Resuscitation drills conducted during the first weeks of the H1N1 outbreak in May 2009 have exposed critical gaps in basic protection among hospital first-responders, according to a Johns Hopkins Children’s Center study.

 

Failing to use personal protection such as gowns, glasses, respirator masks and gloves during infection outbreaks makes hospital staff vulnerable to infection and increases the risk for transmission to patients, the researchers say.

 

The findings, presented May 4 at the Pediatric Academic Societies meeting, emphasize the need for repeat mock drills, the researchers say, and suggest that personal-protection exercises should be included in monthly mock crisis sessions held at the Johns Hopkins Children’s Center.

 

“Having another contagious outbreak is a matter of when, not if, and the time to master protection techniques is now, before it hits us,” said study lead investigator Christopher Watson, a pediatric critical-care fellow.

 

(Continue . . . )

»» Read More

NPI’s and Influenza

 

 

# 4539

 

 

NPIs are Non-Pharmaceutical Interventions – ways to reduce the spread of a disease - and have been a frequent topic in this blog over the years.   

 

NPI’s can be as simple as hand hygiene, covering your coughs, and avoiding crowds, or can involve the use of personal protective barriers like N95 or surgical masks, latex or vinyl gloves, and eye protection.

 

School closures, public education, staying home when sick, and engineered barriers to avoid exposure are also examples of NPIs.

 

And the evidence to date is these steps, if widely implemented, can make a real difference in the spread of an epidemic like Influenza.

Pharmaceutical solutions, most notably vaccines, take months to develop and deploy.  The next pandemic flu to erupt may not be nearly as mild as the 2009 strain, and may hit far more suddenly. 

 

The goal, in those early months before a vaccine becomes available, is to reduce the spread of the virus as much as possible.  In this way, the burden on health care facilities, and toll of absenteeism and on the lives of those effected can be reduced.

 

 

 

NPI’s have been described as being like slices of Swiss cheese, with each containing large holes through which the virus can pass, but when stacked on top of each other, can provide an effective barrier.

 

While it is known that these measures can help reduce influenza transmission, there are many open questions regarding their relative merits, cost effectiveness, and optimum combination.  

 

Unknown too, is exactly how influenza is transmitted.   

Large droplet spread, via coughing and sneezing, is assumed to be the primary mode of transmission, but the exact role of fomites (contaminated inanimate objects we may touch), and the role of fine aerosolized particles are only beginning to be understood.

 

Allison E. Aiello of the University of Michigan is one of the researchers that has been looking for answers to these questions, and I’ve featured her team’s work a number of times.

 

Michigan NPI Study: A Closer Look

Study: Effectiveness of NPIs Against ILI's

Study: NPI's Can Help Prevent Spread Of Flu-Like Illnesses

 

Aiello’s team has recently published their findings in the May issue of the American Journal of Infection Control.   The abstract is available, but it requires a subscription to access the main article.

 

Luckily we’ve a pretty good summary available from MedPage Today. First the abstract, then the link to the MedPage article.

 

Research findings from nonpharmaceutical intervention studies for pandemic influenza and current gaps in the research

Allison E. Aiello, et al.

AJIC: American Journal of Infection Control - May 2010 (Vol. 38, Issue 4, Pages 251-258, DOI: 10.1016/j.ajic.2009.12.007)

In June 2006, the Centers for Disease Control and Prevention released a request for applications to identify, improve, and evaluate the effectiveness of nonpharmaceutical interventions (NPIs)—strategies other than vaccines and antiviral medications—to mitigate the spread of pandemic influenza within communities and across international borders (RFA-CI06-010).

These studies have provided major contributions to seasonal and pandemic influenza knowledge. Nonetheless, key concerns were identified related to the acceptability and protective efficacy of NPIs. Large-scale intervention studies conducted over multiple influenza epidemics, as well as smaller studies in controlled laboratory settings, are needed to address the gaps in the research on transmission and mitigation of influenza in the community setting. The current novel influenza A (H1N1) pandemic underscores the importance of influenza research.

 

 

 

Non-Drug Approach Can Slow Spread of Pandemic Flu

By Michael Smith, North American Correspondent, MedPage Today

Published: April 30, 2010

Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
 

Nonpharmaceutical interventions, such as handwashing campaigns, can have a significant impact on the spread of the pandemic H1N1 flu, researchers said.

 

But an analysis of 11 CDC-supported studies reveals key gaps in the research, according to Allison Aiello, PhD, of the University of Michigan Ann Arbor, and colleagues.

 

The researchers, writing in the May issue of the American Journal of Infection Control, called for large intervention studies, conducted over multiple flu seasons, to assess the impacts of such things as handwashing, cough etiquette, and mask wearing.

 

Research is also needed into the psychosocial and cultural barriers that make some groups reluctant to accept such measures, Aiello and colleagues said, as well as lab studies to pin down how the flu is transmitted.

(Continue . . .)

»» Read More