Table 1.

Outbreak investigations of SARS‐CoV‐2 in schools and ECECs outside Australia

Educational facility	Location	Period (2020)	Community incidence rate 90 , 91 , 92	Mitigation strategies	Findings
ECECs
	Rhode Island, USA 46	1 Jun–31 Jul	271/100 000	Masks for adults, daily symptom screening, enhanced cleaning and disinfection	52 cases (30 students, 20 staff, 2 parents), in 29 ECECs In 20 (69%) settings no transmission occurred, secondary transmission likely occurred in 4 (7%) settings, one of which had poor compliance to implemented mitigation strategies
	Salt Lake City, USA 47	1 Apr–10 Jul	860/100 000 (Utah)	Mask use in adults, hand hygiene, frequent cleaning/disinfection of high touch surfaces	17 ECECs had an outbreak† 3 outbreaks described: primary cases were all staff 19 secondary cases: (7 staff members, 12 students); 1 ECEC had 14 secondary cases)
Schools
	Israel 44	May 2020	63/100 000	Daily health reports, hygiene, facemasks, social distancing and minimal interaction between classes	2 index cases 178 secondary cases Large class sizes of 30–35 students in small poorly ventilated classroom settings were likely contributing factors to spread
	Ireland 48	1 Mar–13 Mar	2/100 000	No mitigation strategies	6 cases (3 students and 3 adults) attended 6 schools. No secondary cases
	South Korea 49	20 May–11 Jul	1/100 000	Universal mask use, plastic barriers between desks, increased hand hygiene	44 student cases in 38 schools More than 13 000 students and staff were tested Transmission only occurred in 1 primary school setting (2 secondary cases)
	Italy 50	14 Sep–5th Oct	64/100 000	Mask use, hand hygiene, physical distancing	1350 COVID‐19 primary cases (1059 students, 145 teachers, 146 other staff members) attended 1212 schools No secondary cases in 90% of settings Only 1 high school had a cluster of more than 10 cases.
	Germany 51	28 Jan–31 Aug	295/100 000	Hygiene measures, staggering timetables, restricting class sizes, face masks, physical distancing	48 outbreaks† described 2 high schools had >10 cases
	Norway 45	28 Aug–11 Nov	299/100 000	Hygiene measures, physical distancing,	13 primary student cases (8 aged between 5–10 years and 5 aged 11–13 years) Total 292 school contacts There were 3 secondary cases (2 students and 1 adult)
	Finland 52 (Helsinki)	Mar 2020	26/100 000	None specified	2 primary cases (1 student and 1 adult) 184 contacts; 140 tested 7 secondary cases (all from staff primary case)
	New York City 53	9 Oct–18 Dec	4178/100 000	Screening, mask use, distancing of desks, reduced class sizes	2221 primary cases (889 students, 1342 staff) 36, 423 contacts 191 secondary cases
Both ECECs and schools
	England 54	1 Jun–17 Jul	54/100 000 (UK)	Cohorting of students into groups	928 000 recommenced face to face learning 177 settings with COVID‐19 case 122 settings with no further transmission Transmission occurred most often between adult staff members
	Italy (Reggio Emilia province) 55	(1 Sep–15 Oct)	154/100 000 (Emilia Romagna)	Mandatory mask use in secondary school settings, physical distacing of desks in schools, mixing of classes minimised	43 primary cases (38 students, 5 teachers) in 36 settings (8 ECEC, 10 primary, 18 secondary schools). 39 secondary cases in 13 schools. Attack rate in secondary schools (6.64%) higher than primary schools (0.44%)
	Singapore 56	1 Feb– 30 Mar	16/100 000	Cohorting of students into groups, staggered recess breaks, suspension of extracurricular activities	3 cases (2 students and 1 staff) in 1 high school and 2 childcare settings Transmission occurred between 16 staff members in an ECEC No students tested positive

†Outbreak defined as 2 or more confirmed COVID‐19 cases within a setting. The studies from Salt Lake City and Germany limited their analysis to outbreak settings with 2 or more cases and thus described attack rates are likely to be grossly overestimated for the population. [Correction added on 12 July 2021, after first online publication: In the third row, ‘School, Israel’ of the third column, ‘Period (2020)’, ‘Mar 2020’ has been amended to ‘May 2020’.]