A comparison of children and adults hospitalized with COVID-19 reveals pediatric patients, who had better outcomes and shorter hospital stays, displayed altered immune responses and more limited production of antibodies against infection. While these preliminary findings are descriptive and do not establish a causative relationship, the study hints that these immune differences could help explain why children have consistently developed less severe cases of COVID-19 than adults during the pandemic. COVID-19 has caused more than 29 million cases and 929,000 deaths globally, and high hospitalization rates from the disease have overwhelmed healthcare systems in many cities. Clinicians have noted that children and young people have milder symptoms and rarely progress to life-threatening respiratory complications - the opposite of what has been observed with other viral infections such as respiratory syncytial virus. However, the basis for these clinical differences has been unclear. Carl Pierce and colleagues compared data from 65 children and youths (under 24 years of age) and 60 adults hospitalized with COVID-19 in metropolitan New York. The infected children - including some who had the emerging complication known as multisystem inflammatory syndrome - were less likely to require mechanical ventilation (8% vs 37%) and had lower mortality (3% vs 28%) than the adults. However, adults showed higher antibody production and T cell responses to the viral spike protein, but lower amounts of inflammatory molecules like IL-17A and IFNγ that are involved in innate immunity. "The results provide new insights into potential mechanisms that may contribute to age-related differences in disease resolution ... and may have implications for ongoing efforts with convalescent plasma and the development of therapeutic antibodies," Pierce et al. write.
Science Translational Medicine