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expert reaction to a preprint from PHE looking at SARS-CoV-2 infection and transmission in educational settings

Public Health England (PHE) have released a preprint study, an unpublished non peer-reviewed paper, looking at SARS-CoV-2 infection and transmission in educational settings.


Prof Paul Hunter, Professor in Medicine, The Norwich School of Medicine, University of East Anglia, said:

“This is a useful paper describing the experience of school outbreaks of COVID 19 after the partial opening of schools in England in early June. The main year groups that were open at the time were years 1 and 6 so mainly junior and primary schools.

“The investigators identified 30 outbreaks in educational establishments of which 15 were staff-to-staff transmissions, 7 staff-to-student,  6 student-to-staff and 2 were student-to-student. So in about 26% out outbreaks the index case was a child. Probably the most important information is given in table 1 but I am afraid that I am struggling to understand some of the calculations. Table 1 gives calculated attack rates per 100,000 students per day for the month of June. As I understand it for primaries there were 43 children diagnosed with COVID 19 during the month. The table also states that the average number of children attending per day was 519,727. They then go on to calculate a rate of 8.3 per 100,000 students per day by dividing 43 by the average number of children attending per day. Given that there were 22 school days in June should this be 8.3 per 100,000 per student months? I apologise if I have misinterpreted something. 

“In any event what does this tell us about the role that schools may have in the transmission of COVID-19? It should be said that there is no argument that young children are highly unlikely to suffer severe illness even if they acquire COVID-19 infection. This paper does confirm that outbreaks can occur in schools and that children can be the index cases. The issue is whether schools themselves can act as amplifiers of the epidemic and so increase transmission in the community rather than do schools pose a risk to children.

“The evidence to date on whether schools increase the community risk of COVID-19 is somewhat mixed with some doubting that children were likely to spread the infection or at least be one of the more important transmitting group. A recent paper from Public Health England claimed that “Our findings provide further evidence against the role of children in infection and transmission of SARS-CoV-2” (Ladhani), though I amongst others did not think their conclusions were supported by the evidence. Another recent Australian study (Macartney) found little evidence of ongoing transmission risk in schools but numbers of cases were actually quite small. On the other hand Stein-Zamir reported a large school outbreak in a secondary school Israel which could be traced back to two students. Szablewski reported an outbreak in a summer camp for children with a high attack rate.

“So where does this leave us? One of the particularly useful observations to come out of this new paper is that the probability of school outbreaks is related to the incidence in the general community. Consequently it is difficult to extrapolate from a study undertaken at a time when most school children were not in school, and those that were, were mainly on under 11 years old, to this autumn when the general incidence may be somewhat higher. A recent large study of contact tracing from South Korea ( found that children over 10 were the most likely age group if infected to transmit the infection to household contacts, though rather lower to non-household contacts.

“So in conclusion whilst there is still uncertainty over the science we certainly cannot discount schools as a likely accelerator of the epidemic in the wider community. In my view the balance of evidence is that older children (>10 years) may be the more important age group. Nevertheless I think Professor Whitty is correct when he says that missing schools is worse for children than the virus. The DHSC have produced guidance to schools and if this is followed this should help reduce the risk. However, once schools return and if the general incidence in the UK increases we are likely to see many more school-based outbreaks with considerable disruption this autumn.”  

Ladhani SN, Amin-Chowdhury Z, Davies HG, Aiano F, Hayden I, Lacy J, Sinnathamby M, de Lusignan S, Demirjian A, Whittaker H, Andrews N. COVID-19 in children: analysis of the first pandemic peak in England. Archives of Disease in Childhood. 2020 Aug 12.

Macartney K, Quinn HE, Pillsbury AJ, Koirala A, Deng L, Winkler N, Katelaris AL, O’Sullivan MV, Dalton C, Wood N, Brogan D. Transmission of SARS-CoV-2 in Australian educational settings: a prospective cohort study. The Lancet Child & Adolescent Health. 2020 Aug 3.

Szablewski CM. SARS-CoV-2 Transmission and Infection Among Attendees of an Overnight Camp—Georgia, June 2020. MMWR. Morbidity and mortality weekly report. 2020;69.

Stein-Zamir C, Abramson N, Shoob H, Libal E, Bitan M, Cardash T, Cayam R, Miskin I. A large COVID-19 outbreak in a high school 10 days after schools’ reopening, Israel, May 2020. Eurosurveillance. 2020 Jul 23;25(29):2001352.


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