Study: School closures slow spread of pH1N1: study

[Shiloh]

Source: http://medicalxpress.com/news/2012-02-school-closures-ph1n1.html

School closures slow spread of pH1N1: study
February 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)...

 

[tetano]

Re: Study: School closures slow spread of pH1N1: study

Annals of Internal Medicine

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

From McMaster University, Hamilton, Ontario; University of Calgary, Calgary, Alberta; and Edmonton Clinic Health Academy, Edmonton, Alberta, Canada.

Abstract

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.

Objective: To examine correlations between the incidence of pandemic H1N1 (pH1N1) influenza in Alberta, Canada, in 2009 and school closures or weather changes, and to estimate the effects of school closures and weather changes on pH1N1 transmission.

Design: Mathematical transmission models were fit to data that compared the pattern of confirmed pH1N1 cases with the school calendar and weather patterns.

Setting: Alberta, Canada, from 19 April 2009 to 2 January 2010.

Data Sources: 2009 virologic test results, 2006 census data, 2009 daily temperature and humidity data, and 2009 school calendars.

Measurements: Age-specific daily counts of positive results for pH1N1 from the complete database of 35 510 specimens submitted to the Alberta Provincial Laboratory for Public Health for virologic testing from 19 April 2009 to 2 January 2010.

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.

Limitations: Data probably represent a small sample of all viral infections. The mathematical models make simplifying assumptions in order to make simulations and analysis feasible.

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.

Primary Funding Source: Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council of Canada, and Public Health Agency of Canada.

http://www.annals.org/content/156/3/173.abstract

 

[tetano]

Re: Study: School closures slow spread of pH1N1: study

EDITORIAL

Getting Schooled: School Closure, Age Distribution, and Pandemic Mitigation


David N. Fisman, MD, MPH

From University of Toronto, Toronto, Ontario M5T 3M7, Canada.

Despite the gains in antimicrobial therapy and vaccines that have come in the past 100 years (1), epidemics and pandemics (synchronized, global epidemics) remain an important source of morbidity, mortality, and costs in high-, middle-, and low-income countries. Epidemics can be thought of as self-perpetuating, exponential growth processes; because infections are communicable, the more cases you have, the more cases you will get, as long as the population contains susceptible persons to infect.

Epidemiologists refer to the key index of this type of growth as the reproductive number of an infectious disease?the number of new (incident) cases created by each old (prevalent) case before the prevalent case recovers (2). Reproductive numbers are the product of 3 core components: how infectious a person is, the duration of infectiousness of a person, and how many contacts that person has. Epidemic mitigation strategies that seek to reduce the latter component of the reproductive number (contact between infectious and susceptible persons) are often referred to as social-distancing measures.

Social-distancing measures may include closing schools, suspending religious services, and canceling large public gatherings. A famous study in contrasts with respect to the implementation of social distancing for influenza pandemic control occurred in St. Louis and Philadelphia during the severe influenza A(H1N1) pandemic in 1918 to 1919 (3). Authorities in Philadelphia declined to impose social-distancing measures (including, famously, not canceling a parade through the center of the city that drew large crowds) until the epidemic was severe. In contrast, St. Louis proactively and aggressively restricted religious and social gatherings and closed schools early in its epidemic, and the effect of influenza seems to have been greatly mitigated (3). Whether the divergent courses of St. Louis and Philadelphia were attributable to social-distancing measures or whether the willingness to implement such measures reflected ?


http://www.annals.org/content/156/3/238.extract