Antibody boosting and short-term durability following SARS-CoV-2 infections in United States longitudinal cohorts, 2020-2024

Abstract

To characterize anti-nucleocapsid (anti-N) IgG binding antibody responses following first PCR-confirmed SARS-CoV-2 infections in a highly vaccinated population, we evaluated antibody boosting and durability in a longitudinal cohort in Michigan. Among 113 participants with paired pre- and post-infection serum specimens tested using a multiplex electrochemiluminescence assay, SARS-CoV-2 infection induced substantial boosting of anti-N IgG concentrations; approximately 80% of participants becoming anti-N seropositive following infection, and 81% of participants demonstrating at least a 4-fold rise in antibody concentrations following infection. Population-level analyses of 66 participants with post-infection serum specimens collected 52-120 days after infection demonstrated sustained anti-N IgG concentrations over time, with no evidence of substantial decline. These findings demonstrate robust boosting and sustained infection-induced anti-N IgG responses in a highly vaccinated population through four months following SARS-CoV-2 infection. This supports the use of anti-N antibodies for longitudinal serosurveillance, including those who are vaccinated.