Abstract
We investigated three SARS-CoV-2 variant B.1.1.7 childcare centre and related household outbreaks. Despite group cohorting, cases occurred in almost all groups, i.e. also among persons without close contact. Children’s secondary attack rates (SAR) were similar to adults (childcare centres: 23% vs 30%; p = 0.15; households: 32% vs 39%; p = 0.27); child- and adult-induced household outbreaks also led to similar SAR. With the advent of B.1.1.7, susceptibility and infectiousness of children and adults seem to converge. Public health measures should be revisited accordingly.
Highlights
We investigated three SARS-CoV-2 variant B.1.1.7 childcare centre and related household outbreaks
As at 3 March 2021, approximately 40% of all randomly selected swabs of all coronavirus disease (COVID-19) cases tested positive for the B.1.1.7 variant [1]
For pre-variant of concern’ (VOC) SARS-CoV-2 strains, close contacts were associated with a secondary attack rates (SAR) of 5% [7] to 13% [8], while non-close contacts were associated with a SAR of 0% [7] to 3% [8]
Summary
These simultaneously occurring outbreaks in childcare facilities provided an opportunity to revisit definitions of ‘closeness’. The above mentioned meta-analysis of pre-VOC studies found a (non-significantly) lower SAR when children aged < 18 years were the PC (7.9%; 95% CI: 1.7– 16.8) compared with SAR when adults were the household PC (15.2%; 95% CI: 6.2–27.4) [11]. A display by age groups showed a U-shaped curve for both B.1.1.7 susceptibility and infectiousness, shifted upwards from non-B.1.1.7 variants, with a low SAR for teenagers, and comparable SAR values for 0–4 and 5–9 year-old children and adults. Even if these possibilities may be true in individual households, it is unlikely to distort the overall picture
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