Children under four at nursery are unlikely to catch Covid-19, a study suggests. 

The study in France looked at children aged between five months and four years attending daycare during lockdown in March to May 2020. It showed they had low rates of SARS-CoV-2 antibodies in their blood – known as seroprevalence – suggesting that overall virus infection rates were low in this population.

The rate of SARS-CoV-2 virus infection in kids was 3.7%, with positive cases likely infected by an adult in their household, rather than whilst at nursery. 

This study, published in the Lancet’s Child & Adolescent Health journal, is one of the first to estimate seroprevalence in preschool settings. Since it was conducted, a number of SARS-CoV-2 variants have emerged, which are not captured in the data.

“Our results suggest that daycare centres are not focus points of SARS-CoV-2 virus infection and that young children are not spreading the virus widely in these environments,” says Dr Camille Aupiais, lead author from Hôpital Jean-Verdier, Paris, France.

“These findings should be reassuring for parents and staff at daycare centres, especially given that the children included in the study have parents who are keyworkers and are thought to be at higher risk during the first wave of the epidemic.”

In all, 14 out of 327 children tested positive for SARS-CoV-2 antibodies and those 14 children came from 13 different daycare centres. In the centre with two seropositive cases, the children had attended separate zones of the daycare centre with no mixing, suggesting that there was no child-child transmission in these cases. 

“Our results suggest that young children are more likely to contract Covid-19 at home, rather than at a daycare centre,” added Dr Aupiais. 

Commenting on the study’s relevance in the UK, Professor Paul Hunter, an expert on infectious diseases at the University of East Anglia tells HuffPost UK the paper provides “further evidence” that pre-school nurseries and daycare for young children are “unlikely to be really important” in the spread of the Covid epidemic.

“We do know that very young children can be infected but that usually such children have asymptomatic or very have mild disease,” he said. “The balance of evidence is that amongst children it is secondary schools aged children that are more implicated in the spread of infection than younger children and this paper supports that.”

However, Dr Julian Tang, honorary associate professor in respiratory sciences and a clinical virologist at the University of Leicester, says we should be “very cautious” in the interpretation and application of these study findings.

We know from multiple studies on other respiratory viruses (flu, RSV, hMPV, parainfluenza viruses) that children do get infected and can reach higher viral loads and shed virus for longer than adults, he says – “and the same seems to be true for Covid-19”. 

“The main difference is that children with Covid-19 seem less symptomatic, so may not be so easily detected if the testing focuses mainly on testing symptomatic children,” he says. “If this is the case, we would expect to find a higher antibody prevalence in children – but this depends on what percentage of children actually develop antibodies to Covid-19 and how long they last.”

Dr Tang adds that the performance of the test kit used in the study may be variable. “Although the reported test sensitivity/specificity looks good on paper, in reality the sensitivity is often much lower and it will depend on what part of the Covid-19 exposure/ infection/ recovery timeline the children are on, as this is a cross-sectional study,” he adds. 

“Especially when emerging from lockdown, the natural exposure rates of Covid-19 might be quite low and not reflect the exposure/transmission intensity when more virus is circulating in the community – in the winter period, for example.”