Secondary attack rates in primary and secondary school bubbles following a confirmed case: Active, prospective national surveillance, November to December 2020, England (Beckmann, 2023)

Powell Annabel A., Ireland Georgina, Baawuah Frances, Beckmann Joanne, Okike Ifeanyichukwu O., Ahmad Shazaad, Garstang Joanna, Brent Andrew J., Brent Bernadette, Aiano Felicity, Hargreaves James, Langan Sinead M., Mangtani Punam, Nguipdop-Djomo Patrick, Sturgess Joanna, Oswald William, Halliday Katherine, Rourke Emma, Dawe Fiona, Amin-Chowdhury Zahin, Kall Meaghan, Zambon Maria, Poh John, Ijaz Samreen, Lackenby Angie, Elli Joanna, Brown Kevin E., Diamond Sir Ian, Ramsay Mary E., Ladhani Shamez N. 

PloS one 2022;17(2): e0262515. 

Available online at this link 

BACKGROUND: Following the full re-opening of schools in England and emergence of the SARS-CoV-2 Alpha variant, we investigated the risk of SARS-CoV-2 infection in students and staff who were contacts of a confirmed case in a school bubble (school groupings with limited interactions), along with their household members., 

METHODS: Primary and secondary school bubbles were recruited into sKIDsBUBBLE after being sent home to self-isolate following a confirmed case of COVID-19 in the bubble. Bubble participants and their household members were sent home-testing kits comprising nasal swabs for RT-PCR testing and whole genome sequencing, and oral fluid swabs for SARS-CoV-2 antibodies., 

RESULTS: During November-December 2020, 14 bubbles were recruited from 7 schools, including 269 bubble contacts (248 students, 21 staff) and 823 household contacts (524 adults, 299 children). The secondary attack rate was 10.0% (6/60) in primary and 3.9% (4/102) in secondary school students, compared to 6.3% (1/16) and 0% (0/1) among staff, respectively. The incidence rate for household contacts of primary school students was 6.6% (12/183) and 3.7% (1/27) for household contacts of primary school staff. In secondary schools, this was 3.5% (11/317) and 0% (0/1), respectively. Household contacts were more likely to test positive if their bubble contact tested positive although there were new infections among household contacts of uninfected bubble contacts., 

INTERPRETATION: Compared to other institutional settings, the overall risk of secondary infection in school bubbles and their household contacts was low. Our findings are important for developing evidence-based infection prevention guidelines for educational settings.