Humoral cross-reactivity towards SARS-CoV-2 in young children with acute respiratory infection with low-pathogenicity coronaviruses

SARS-CoV-2 infection in children frequently leads to only asymptomatic and mild infections. It has been suggested that frequent infections due to low-pathogenicity coronaviruses in children, imparts immunity against SARS-CoV-2 in this age group. From a prospective birth cohort study prior to the pandemic, we identified children (n=42) with proven low-pathogenicity coronavirus infections. Convalescent sera from these samples had antibodies against the respective seasonal CoVs as demonstrated by immunofluorescence assay. We tested these samples for neutralization of SARS-CoV-2 using virus microneutralization assay. Forty serum samples showed no significant neutralization of SARS-CoV-2, while 2 samples showed inconclusive results. These findings suggest that the antibodies generated in low-pathogenicity coronavirus infections offer no protection from SARS-CoV-2 infection in young children.