Protective humoral immunity in SARS-CoV-2 infected pediatric patients

Abstract

After the rapid spread of SARS-CoV-2 in Wuhan, China, at the beginning of 2020, about 1.5 million confirmed cases and over 80,000 deaths have been reported around 200 countries and territories all over the world and the number continues to increase. However, we still have limited knowledge of this new coronavirus, especially the interaction between SARS-CoV-2 and our immune system. In contrast with infected adults, the children have received more attention because of the lower infection rates and milder symptoms. 1 Less than 1% of infected cases were aged 10 years or younger. 2 Only 3.5% of SARS-COV-2 infected children had lymphocytopenia. 1 It has been reported, coronaviruses, including SARS-CoV, MERS-CoV, and SARS-CoV-2, seem to cause fewer symptoms and less severe disease in children compared with adults. 3 This phenomenon may be related to the differences in the immune responses against the infection of coronaviruses between children and adults. Here, we reported the characteristics of immune response after the SARS-CoV-2 attack in children and found that there is a protective humoral immunity in infected children, in which memory B cells and S-protein specific Abs against the SARS-CoV-2 have been detected. Our observation presents one possible explanation for the milder symptoms in children after exposure to SARS-CoV-2.