A COVID-19 outbreak of 52 people in a large school community in Santiago, Chile was identified on 12 March 12, 9 days after the first Chilean case. The authors were interested in the magnitude of the outbreak and the role students and staff played in it. The school was closed on 13 March and the entire community was quarantined. The authors implemented a home-delivery, self-administered IgG/IgM antibody test and survey to a classroom stratified sample of students and all staff. Antibody positivity rates were 9.9% for 1009 students and 16.6% for 235 staff. Among the students, positivity was significantly associated with younger age, lower grade level, prior RT-PCR positivity, and history of contact with a confirmed case. Among staff, the positivity was significantly higher in teachers and in those previously RT-PCR positive. If they excluded RT-PCR positive people, antibody positivity was found to be significantly associated with fever in both adults and children, abdominal pain in children and chest pain in adults. Among antibody positive patients, 40% of students and 18% of staff reported no symptoms. Therefore teachers were more likely to be affected during the outbreak and younger children were at higher infection risk, likely because the index case(s) were teachers and/or parents from preschool.
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