SARS-CoV-2 spike protein induces a differential monocyte activation that may contribute to age bias in COVID-19 severity.

A strong bias related to age is observed in COVID-19 patients with pediatric subjects developing a milder disease than adults. We hypothesized that a specific SARS-CoV-2 effect conjugated with preexisting differences in the immune systems may explain this. Using flow cytometry, we investigated basal immune differences in a cohort consisting of 16 non-infected young and 16 aged individuals and further leveraged an in vitro whole blood model of SARS-CoV-2 infection so that functional differences could be mined as well.