Distinct B cell repertoires characterize patients with mild and severe COVID-19 [VDJ]

Protective immunity against COVID-19 likely depends on the production of SARS-CoV-2 binding plasma cells and memory B cells after infection or vaccination. Previous work has shown evidence that germinal center reactions, a critical component of the B cell response, are disrupted in severe COVID-19. This may adversely affect protective immunity from re-infection. Consistent with an extrafollicular B cell response, severe COVID-19 patients have large scale changes in B cell populations such as elevated frequencies of clonally expanded, class switched, unmutated plasmablasts. However, it is not clear whether mild or asymptomatically infected individuals show similar differences in B cell repertoires. Here, we use single cell RNA sequencing of B cells to show that, in contrast to hospitalized COVID-19 patients, mildly symptomatic COVID-19 subjects have B cell repertoires skewed towards clonally diverse, somatically hypermutated memory B cells approximately 30 days after the onset of symptoms. This provides evidence that B cell responses are less disrupted in mild COVID-19, and that the infection resolves with the production of memory B cells. Characterization of B cell response in mild symptomatic COVID-19 patients