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

The study examined anti-nucleocapsid (anti-N) IgG antibody responses following first confirmed SARS-CoV-2 infection in a highly vaccinated population in Michigan. Among 113 participants with paired serum samples collected before and after infection, the infection induced substantial boosting of anti-N IgG concentrations, with approximately 80% of participants becoming anti-N seropositive and 81% showing at least a 4-fold increase in antibody concentrations. In a group of 66 participants with samples collected 52-120 days after infection, sustained anti-N IgG concentrations were observed over time with no evidence of substantial decline. The results demonstrate robust antibody boosting and sustained infection-induced anti-N IgG responses over four months following SARS-CoV-2 infection. These findings support the use of anti-N antibodies for longitudinal serological surveillance including vaccinated individuals.