Transmission of SARS-CoV-2 by children to contacts in schools and households: a prospective cohort and environmental sampling study in London

Understanding SARS-CoV-2 Delta and Omicron variant transmission and vaccine impact in schools and child-care settings in Australia: a population-based study

“…However, these outbreaks did not result in lengthy school closures or disruption. Importantly, our study shows that the attack rates in schools, even with omicron remain considerably lower than in other settings such as households 27 , 31 and social events. 22 Similar to our previous study, 5 we found that staff members were over-represented among primary and secondary cases compared with children.…”

“…Very few studies have examined SARS-CoV-2 transmission during periods of delta or omicron circulation 23 , 27 , 28 , 29 ; even fewer have accounted for vaccination status, included the omicron variant or had high rates of testing, including in asymptomatic contacts as our study has. A study in schools (80,980 contacts) in New York City, USA 28 between October 10 to December 5, 2021 reported an overall SAR of 0.7% in delta incursions, with 0.6% in 2-dose vaccinated contacts, and 0.9% in unvaccinated contacts, however the proportion of contacts who had testing and type of test was not reported.…”

“…Another study in London, England examined eight schools and associated households until July 2021 during delta and ancestral virus periods but did not compare attack rates by variant or vaccination status. 27 A Swiss school reported a high attack rate of 44.9% (31 cases from 69 tested contacts) from an omicron outbreak due to multiple simultaneous incursions, but this was the experience of one school and may not be generalisable across all schools. 29 …”

Risk factors and vectors for SARS-CoV-2 household transmission: a prospective, longitudinal cohort study

“…Hand swabs and surface swabs were tested for RNA presence at the Department of Infectious Disease, Imperial College London, London, UK ( appendix p 4 ). 3 PCR-positive hand and surface swabs with a cycle threshold (Ct) of less than 33 were subjected to viral culture in a mammalian cell line-based in vitro assay ( appendix pp 4–5 ). Swabs were maintained at 4°C for 36–72 h until culture was performed, reflecting the time for transportation from residents' homes and laboratory storage while RT-PCR was performed.…”

“…Although previous studies have documented the presence of SARS-CoV-2 RNA on household surfaces, 3 , 4 as well as in exhaled and ambient air from hospitalised patients with COVID-19, 5 , 6 its detection on potential vectors has not hitherto been shown to correlate with transmission. This gap in knowledge hampers accurate modelling of disease transmission and development of evidence-based public health guidance, 7 , 8 which remain important given the ability of SARS-CoV-2 to spread through highly vaccinated populations.…”