Most schools in the four countries Trump mentioned have now reopened, although restrictions on how the kids can mingle are still in place. However, apart from Sweden, which has been an outlier in Europe as the only country without a strict lockdown, the countries cited by the US President have reopened schools in a careful, gradual way.

Scientific advice on when and how to reopen schools has varied across different countries. Data so far has shown that children seem to be less at risk of contracting Covid-19, and when they do catch the virus, they are likely to have only mild symptoms. But a number of cases of a rare but serious inflammatory syndrome in children who tested positive for coronavirus have sparked some worries about the impact the disease has on kids.

“The evidence from many countries around the world is that transmission in schools is very low,” said Russell Viner, president of the UK’s Royal College of Paediatrics and Child Health, in a statement. Viner also said that most children catch Covid-19 from adults in their household rather than schools.