An update on the epidemiology of pediatric COVID-19 in Brazil

T he coronavirus disease 2019 (COVID-19) pandemic impacted the whole world, challenging health systems, crashing economies, and taking the lives of over 4.5 million people.In a short period of time, to contain the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the world has adapted to a new reality of quarantines or lockdowns, mask-wearing, and social distancing.No other condition in human history has been so widely studied, leading to the development of safe and effective COVID-19 vaccines in record time.Since the beginning of the pandemic, it is clear that newborns, children, and adolescents are less impacted by this emerging condition than adults.Most of them present mild symptoms; hospitalization and death of pediatric patients are rare. 1 This fact is highly unusual, since younger children are more vulnerable to most respiratory viruses, such as influenza or syncytial respiratory virus (SRV), with a higher risk of unfavorable outcomes.There are multiple pathophysiological mechanisms involved in SARS-CoV-2 pediatric infection, some of which could explain this contradiction.Children have fewer angiotensin-converting enzyme (ACE) receptors, leading to decreased cell infection, 2 and pre-existing neutralizing antibodies and T-cell immunity to seasonal coronavirus might cross-protect against COVID-19.3 More recently, the focus has been over the role of the innate immune response in pediatric populations, and on how a less specific and more swift immune response might be implicated in protecting children.4,5 Despite that, children and adolescents may have poor outcomes, including severe and unique manifestations.6 Indeed, the recognition of the multisystem inflammatory syndrome in children (MIS-C), a life-threatening condition with high rates of morbimortality, reinforces the importance of children and adolescent protection, and the need of advancing COVID-19 research for pediatric patient populations.7,8