July 24, 2020

A Large COVID-19 Outbreak in a High School 10 Days after Schools’ Reopening, Israel, May 2020

Category: Article Summary

Topic: Transmission

• An extensive outbreak investigation in a school (grades 7-12) in Jerusalem (Israel) found evidence of SARS-CoV-2 transmission within the school. After re-opening on May 17 after a two month closure, the first school outbreak occurred 10 days later. There was an indication that transmission was largely confined to certain grades, and to specific classrooms within those grades.  
• As part of the outbreak investigation, SARS-CoV-2 testing was conducted on 1,161 of 1,164 students and 151 of 152 staff members. Overall, 13.2% of students and 16.6% of staff had SARS-CoV-2 infection, of whom 43% of students and 76% of staff were symptomatic. One emergency room visit was recorded and there were no hospitalizations. 
• Prevalence of SARS-CoV-2 among students in the school at the time of testing was highest in grades 7-9 (17.3% to 32.6%) compared to grades 10-12 (1.6%-4.5%). Even within the younger grades, cases appeared to be clustered within specific classrooms.  
• An environmental school inspection reported crowded classes (35–38 students per class). While facemasks were initially required, this mandate was removed during a heatwave that occurred within days of the school re-opening. 
• Contact tracing of close contacts of cases from the school identified 87 additional cases. [EDITORIAL NOTE: From this report, it is not clear how many close contacts were tested or the proportion of contacts who were positive for symptomatic versus asymptomatic cases] 

Stein-Zamir et al. (July 23, 2020). A Large COVID-19 Outbreak in a High School 10 Days after Schools’ Reopening, Israel, May 2020. Eurosurveillance. 
https://doi.org/10.2807/1560-7917.ES.2020.25.29.2001352