But scientists warn that the findings do not mean that children should not be vaccinated against COVID-19.<\/p>\n\n\n\n
Authors: Heidi Ledford<\/a> July 4, 2022 NATURE<\/p>\n\n\n\n Children and adolescents who had not been vaccinated against COVID-19 mounted a long-lasting immune response to infection with the Delta variant of the coronavirus SARS-CoV-2<\/a>, according to a large study of Israeli health records1<\/a><\/sup>. The study, which has been published as a preprint on medRxiv, has not yet been peer reviewed.<\/p>\n\n\n\n A year and a half after an infection, the resulting immune response was still about 80% effective at preventing reinfection, the study found. But it isn\u2019t clear how the results will translate to infections by coronavirus variants of the Omicron lineage<\/a>, which is now dominant in many countries. \u201cThere is a much less-robust immune response to Omicron among previously infected and\/or vaccinated individuals,\u201d says Yvonne Maldonado, chief of paediatric infectious diseases at Stanford School of Medicine in California. \u201cSuch immune responses are also significantly less durable.\u201d<\/p>\n\n\n\n Even so, the study \u2014 which includes data from about 300,000 children and adolescents \u2014 is a welcome addition to the relatively small pool of knowledge about immune responses to SARS-CoV-2 in children<\/a>, says paediatrician Nigel Crawford at the Murdoch Children\u2019s Research Institute in Melbourne, Australia, who studies vaccinology. \u201cThey\u2019re a group for which we haven\u2019t seen a huge amount of data to date,\u201d he says.<\/p>\n\n\n\n The study\u2019s authors collected data on coronavirus infections from Maccabi Healthcare Services, an Israeli health-insurance plan. They focused on the risk of infection from 1 July to 13 December 2021, when the Delta variant was dominant in Israel.<\/p>\n\n\n\n The team found that unvaccinated children and adolescents were 89% less likely to be infected with SARS-CoV-2 3\u20136 months after their first infection than were children who had not previously been infected. For the 12\u201318 age group, this protection against reinfection dropped to 82.5% from 9 months to a year after infection and remained at around that level until up to 18 months post-infection.<\/p>\n\n\n\n Children aged 5\u201311, however, maintained the same level of protection. That, says Crawford, could fit with observations that young children often experience milder COVID-19<\/a> than do adolescents and adults.<\/p>\n\n\n\nWhen Delta dominated<\/h2>\n\n\n\n