cohort_flow_chart a Searched for all records in: Web of Science Core Collection                       For any record that contains in title or abstract the term: school AND contains in title or abstract one or more of the terms: covid, coronavirus, COVID-19, SARS-CoV-2, 2019-nCoV, HCoV-19, hCoV-19.                       Total records retrieved N =1237 b Removed records that met one or more the following conditions: same corresponding author, article type = correction or news item, topic not relevant by hand-inspection, no email. Total records removed N = 143 a->b c Included records: N = 1101 a->c d Identified the corresponding author, and retrieved their emails when available: N = 1101 c->d e Currently invited authors: N = 548 d->e f Undelivered emails: N = 15 e->f g Net number invited authors: N = 533 e->g