evidence: Incidents of critical covid-19 in children remain rare, even though the delta and omicron variants have proved considerably more adept at infecting children than previous variants. In the early stages of the pandemic, estimates indicated that children were less likely to become infected with SARS-CoV-2 in the first place.1 And one of the first major retrospective studies about children and covid-19, by Chinese scientists in the first year of the pandemic, found that up to 90% of paediatric cases were asymptomatic, mild, or moderate.2 "Children are more likely than adults to have asymptomatic or mild infections," says Anna Sick-Samuels, assistant professor of paediatrics at Johns Hopkins Medical School. "The majority of children hospitalised with severe covid-19 have been unvaccinated, and many have had additional comorbidities." Sick-Samuels describes children with type 2 diabetes or obesity as being most at risk of developing severe covid-19. UK studies have found children with neurodisabilities or multiple comorbidities to be especially vulnerable to hospital admission or death.34