There are now more than 164 million total confirmed cases of coronavirus disease 2019 (Covid-19) worldwide. The disease has spread globally, and Brazil is among the top three worst-hit countries. According to the US Centres for Disease Control and Prevention (CDC ), the majority of confirmed Covid-19 cases are seen in adults ages 18–64 years, but cases have been reported in children.

While most of these cases are mild, some children may develop a severe inflammatory response. Recent data from Brazil has shown that infants and children are dying at unusually high rates in the country due to Covid-19. Healthcare personnel are struggling to understand why the virus is having such a big impact on children, but suspect it could be the result of a variant.

Brazil’s ministry of health has so far reported 832 deaths in children aged five years and younger due to Covid-19. Comparable data are limited because different countries track the impact of the virus in different ways. The US, however, has reported significantly fewer deaths in children younger than four years of age. The US population is about 1.5 times greater than that of Brazil, but the US has reported 139 deaths in children younger than four years of age since the pandemic began.

The higher mortality rates in young children in Brazil are thought to be related to the P.1 variant, first detected in Japan in travellers from Brazil. This variant is thought to be more infectious and lethal than the original strain. The P.1 variant has spread rapidly throughout Brazil and quickly overwhelmed the healthcare system. There is evidence that the P.1 variant is leading to higher death rates among pregnant women, and causing women with the virus to give birth to stillborn or premature babies.

Other factors contributing to the higher death toll in Brazil may include less testing in children, resulting in delayed medical intervention. Physicians may be less likely to suspect and test for Covid-19 during examinations because the majority of severe cases have occurred in adults and symptoms in children may differ from those commonly reported in adults. There is also a lack of data on the effect of variants in young children because of the rapid pace at which the SARS-CoV-2 virus is mutating, and the understanding of the disease is still being developed.

As well as this, testing children may become less of a priority when there is a shortage of Covid-19 tests. The current strain circulating in Brazil may also be more likely to trigger a severe immune response in children, known as paediatric multisystem inflammatory syndrome or multisystem inflammatory syndrome in children (MIS-C). MIS-C often affects the heart and can lead children to experience toxic shock, making early medical treatment critical to recovery.

Further observational studies are necessary to understand the immune response that Covid-19 triggers in children and the effects of SARS-CoV-2 variants in children. More data collection will lead to a better understanding of how the virus works and increase early detection in young children.