- 21 years of surveillance data on influenza related illnesses in France found on average, children reduce their contact with others by 25% during school holidays, and holidays prevent about 1 in 6 seasonal influenza cases each year. 


Santa Clara University

Historical instances of school closures—ranging from scheduled holidays and teacher strikes to reactive shutdowns across different regions—provide valuable data on their effectiveness in mitigating viral transmission. Analyzing these cases during various influenza pandemics and SARS outbreaks helps to assess the overall impact of school closures on disease spread.

Past School Closures and Their Impacts on Viral Outbreaks and Pandemics

Cauchemez, S., Ferguson N.M., Wachtel C., Tegnell A., Saour G., Duncan B., Nicoll A. (2009, August). Closure of schools during an influenza pandemic. The Lancet Infectious Diseases, 9(473-81). 

Closure of schools during an influenza pandemic

- Schools closed for 2 weeks right after the peak of the influenza outbreak 
- Examining the attack rates before and after closure showed that this was an effective strategy to lower the spread, but after a peak, there is going to be a reduction in cases anyway. 
- Taking a closer look, researchers found no significant effect of the closure of schools on the spread of the outbreak. 

Hong Kong school closure in March 2008 

School holidays in France


- In most cases, school closure was delayed until about 50-75% of the students became ill 
- Local decisions rather than national, which made local schools reluctant to close.
- Overall, the school closure was ineffective in reducing cases because school closure decisions were made too late. 

School closure in France during the 1957 pandemic

- Interventions: school closure, closing churches, banning mass gatherings, case isolation, disinfection and hygiene strategies, required masks
- However, the type and timing of these interventions was different across cities. 
- Interventions that were prolonged and implemented early resulted in positive health benefits, with an estimated reduction in mortality by 10-30% and up to 50% reduction in peak mortality. 


1918 influenza pandemic in US cities 

- During an influenza outbreak, the teacher strike caused a closure of schools. Looking at the number of cases 2 weeks before the strike and 2 weeks of the strike, a significant reduction in physician and emergency department visits, as well as respiratory tract infection diagnoses, was observed during the strike. 
- When the strike ended and students returned to school amidst the outbreak, doctor visits and cases of respiratory tract infections rebounded. 

Teacher strike in Israel in 2000

- 2003 SARS Outbreak
- 2009 H1N1 Pandemic 


Past school closures from viral outbreaks in Taiwan

- A review of the 2003 SARS outbreak in Singapore noted that containment measures included a twice daily mandatory temperature screening of all children aged 6-16 years in schools. 
- Although there were children diagnosed with SARS in Singapore, none were identified through daily temperature screenings at school. 
- All educational facilities were closed for 3 weeks along with the suspension other activities to prevent the congregation of large groups of children. 


2003 SARS Outbreak in Singapore

- Schools in Beijing were closed approximately 6 weeks after the beginning of the outbreak, and remained closed for over 2 months. 
- Pang and colleagues concluded that school closures made very little difference in preventing the spread of SARS in Beijing, due to the fact that there were low attack rates in schools before closure and low prevalence of SARS in children. 
- Cowling and colleagues estimated the effective R for each day of the Beijing SARS outbreak, noting that school closures occurred after the R had dropped below 1 and school closures did not significantly contribute to the control of the outbreak. 
- Class cancellation strategies were used in upper high school and colleges where students would stay on campus but did not attend classes. 
- There were no recorded transmission of SARS in schools during the outbreak in mainland China. 



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