CHMP5 and COVID-19: SARS-CoV-2 spike antibody seropositivity and factors associated with seropositivity among persons with SARS-CoV-2 spike protein seropositivity among persons who completed at least a COVID-19 primary vaccination series and had no history of diagnosed SARS-CoV-2 infection, Kaiser Permanente Northern California, May 2021—January 2022.