Persisting Salivary IgG Against SARS-CoV-2 at 9 Months After Mild COVID-19: A Complementary Approach to Population Surveys

Background Declining humoral immunity in coronavirus disease 2019 (COVID-19) patients and possible reinfection have raised concern. Mucosal immunity, particularly salivary antibodies, may be short lived although long-term studies are lacking. Methods Using a multiplex bead-based array platform, we investigated antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins in 256 saliva samples from convalescent...