RESUMEN
The newly identified strain of the Coronaviridae family called severe acute respiratory syndrome (SARS-CoV-2) recently became the most significant health threat for adults and children. Some main predictors of severe clinical course in patients with SARS-CoV-2 infection are age and concomitant health conditions. Therefore, the proper evaluation of SARS-CoV-2-specific immunity is urgently required to understand and predict the spectrum of possible clinical phenotypes and recommend vaccination options and regimens in children. Furthermore, it is critical to characterize the nature of SARS-CoV-2-specific immune responses in children following asymptomatic infection and COVID-19 and other related conditions such as multisystem inflammatory syndrome (MIS-C), para-infectious and late postinfectious consequences. Recent studies involving children revealed a variety of cytokines, T cells and antibody responses in the pathogenesis of the disease. Moreover, different clinical scenarios in children were observed-asymptomatic seroprevalence, acute SARS-CoV-2 infection, and rarely severe COVID-19 with typical cytokine storm, MIS-C, long COVID-19, etc. Therefore, to gain a better clinical view, adequate diagnostic criteria and treatment algorithms, it is essential to create a realistic picture of the immunological puzzle of SARS-CoV-2 infection in different age groups. Finally, it was demonstrated that children may exert a potent and prolonged adaptive anti-SARS-CoV-2 immune response, with significant cross-reactions against other human Corona Viruses, that might contribute to disease sparing effect in this age range. However, the immunopathology of the virus has to be elucidated first.
RESUMEN
COVID-19 caused by SARS CoV2 emerged in China at the end of 2019 and soon become a pandemic. Since the virus is novel, pre-existing CoV2-specific immunity is not expected to exist in humans, although studies have shown presence of CoV2 cross-reactive T cells in unexposed individuals. Lack of effective immunity in most individuals along with high infectiousness of the virus has resulted in massive global public health emergency. Intense efforts are on to study viral pathogenesis and immune response to help guide prophylactic and therapeutic interventions as well as epidemiological assessments like transmission modeling. To develop an effective vaccine or biologic therapeutic, it is critical to understand the immune correlates of COVID-19 control. At the same time, whether immunity in recovered individuals is effective for preventing re-infection will be important for informing interventions like social distancing. Key questions that are being investigated regarding immune response in COVID-19 which will help these efforts include, investigations of immune response that distinguishes patients with severe versus mild infection or those that recover relative to those that succumb, durability of immunity in recovered patients and relevance of developed immunity in a cured patient for protection against re-infection as well as value of convalescent plasma from recovered patients as a potential therapeutic modality. This is a broad and rapidly evolving area and multiple reports on status of innate and adaptive immunity against SARS-CoV2 are emerging on a daily basis. While many questions remain unanswered for now, the purpose of this focused review is to summarize the current understanding regarding immune correlates of COVID-19 severity and resolution in order to assist researchers in the field to pursue new directions in prevention and control.