Introduction
Since the beginning of the pandemic, epidemiologic data have shown that hospitalization of children and adolescents associated with the severe acute respiratory syndrome (SARS) due to COVID -19 has not significantly impacted this population. They differ from the elderly and adult population with comorbidities, which are specially more susceptible to severe disease progression and complications. (1)
In children, several factors contributed to milder infection, which reduces the number of the significant receptor angiotensin-converting enzyme 2 (ACE2) on the cell surface, resulting in less availability of the receptor, and the presence of other respiratory viruses competing simultaneously and limiting replication of different viruses. In neonates and infants, maternal antibodies provide protective immunity against disease (2,3).
In Brazil, the incidence of SARS associated with COVID -19 totaled 20.846 cases and 856 deaths in the age group between 0 and 19 years by epidemiological week 51 of 2022 (3). In this context, it can also be observed that children were not initially affected by SARS-CoV-2 as much as in the 2009 pandemic caused by H1N1. (4)
It should be noted that the government took several preventive measures to reduce transmission rates in the early stages of the pandemic and after the initial outbreak in Brazil. This dramatically impacted the child population, as schools were closed and classes moved to remote locations, as well as the introduction of social distancing (lockdown), the use of masks, increased availability of Covid-19 testing, and the establishment of field hospitals.
However, after two years of the pandemic, the return of social activities, and the emergence of new variants, among other factors such as mass vaccination of the adult population and the characterization of a new variant of concern called Ômicron in late 2021, there has been an increase in confirmed cases of hospitalized children associated with this new variant and its subtype.