Recent common coronavirus (CCV) infections are associated with reduced COVID-19 severity upon SARS-CoV-2 infection, however the immunological mechanisms involved are unknown . We completed serological assays using samples collected from health care workers to identify antibody types associated with SARS-CoV-2 protection and COVID-19 severity . Rare SARS-CoV-2 cross-reactive antibodies elicited by past CCV infections were not associated with protection; however, the duration of symptoms following SARS-CoV-2 infections was significantly reduced in individuals with higher common betacoronavirus (betaCoV) antibody titers . Since antibody titers decline over time after CCV infections, individuals in our cohort with higher betaCoV antibody titers were more likely recently infected with common betaCoVs compared to individuals with lower antibody titers . Therefore, our data suggest that recent betaCoV infections potentially limit the severity of SARS-CoV-2 infections through mechanisms that do not involve cross-reactive antibodies . Our data are consistent with the emerging hypothesis that cellular immune responses elicited by recent common betaCoV infections transiently reduce disease severity following SARS-CoV-2 infections.