February 16, 2021

expert reaction to preprint modelling the impact of reopening schools in England on SARS-CoV-2 transmission

A preprint, an unpublished non-peer reviewed study, uses weekly contact survey data to estimate the impact of reopening schools on the reproduction (R) number of SARS-CoV-2 in England.

Prof Sarah Lewis, Professor of Molecular Epidemiology, University of Bristol, said:

“These models are based on the likely change in contact patterns from when children are not in school to when they are in school, the authors extrapolate from that to estimate an increase in R.  However, we know from other research that transmission in schools is likely to be low.  Therefore it doesn’t necessary follow that if a child’s contacts change from 5 per week to 30 when they go back to school that there will be 6 times as many infections.  The  authors acknowledge this limitation: “Contacts in different settings likely contribute differently to transmission, but we assumed all contacts make equal contributions to transmission”, which is likely to have a big impact on their results.

“It is also important to not just consider school reopenings in terms of what will happen to the R number, as there are many harms caused by school closures as illustrated by a recent review of the evidence (https://www.medrxiv.org/content/10.1101/2021.02) and these must be balanced against any effects on transmission of the virus.”

Dr Yuliya Kyrychko, Reader in Mathematics, University of Sussex, said:

“This study continues the work conducted by the LSHTM since almost the first lockdown almost a year ago on monitoring the level of contacts between people in different settings and different levels of lockdown restrictions.  Since coronavirus is spread primarily through direct contacts between infected and uninfected people, it is primarily the number, duration and types of contacts between people that control the degree of epidemic spread.  These latest results indicate that once the schools open (either partially, or fully), this will inevitably lead to an increase of contacts between children from different households, their parents and teachers, which may result in the increase of R number, thus possibly triggering another growth in cases.  This is partially mitigated by the rapidly ongoing vaccination campaign, though at present it does not include children, and the overall proportion of individuals, who have received the full two doses, is quite small.  The implication of this is that any changes in the contact structure in population should be introduced very gradually, and should be accompanied by a robust and effective monitoring of disease transmission to make sure any localised outbreaks do not trigger a significant new wave of infections.”

Dr Konstantin Blyuss, Reader in Mathematics, University of Sussex, said:

“This latest work is based on the ongoing CoMix survey, in which a representative sample of population are reporting their contacts, which provides insights about interactions between people in different age groups and different settings.  Using the latest data from this survey and taking into account differences in susceptibility and infectiousness, this study has looked into the effects of separately opening primary or secondary schools, or both.  The results, not unexpectedly, indicate that opening schools can result in the increased mixing of people, leading to an increase in R number.  The biggest increase in R number is observed in the model when both primary and secondary schools are reopened, which would correspond to a higher overall number of contacts between people.  The authors of the study note that disease prevalence may be lower in primary schools, which potentially can reduce the impact of their opening on increasing epidemic spreading wider population.  The preprint also suggested that additional management measures, such as mass testing of school children and rapid contact tracing, might be used to mitigate the potential risk factors of school opening.”

Preprint (not a paper): ‘Estimating the impact of reopening schools on the reproduction number of SARS-CoV-2 in England, using weekly contact survey data’ by James D Munday et al.  This work is not peer-reviewed.

https://cmmid.github.io/topics/covid19/comix-schools.html?678

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www.sciencemediacentre.org/tag/covid-19

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