Tracking Immunity: Increased number of COVID-19 boosters increases the longevity of anti-RBD and anti-RBD neutralizing antibodies

Abstract Background/Objectives Since the World Health Organization declared COVID-19 a pandemic in March 2020, the virus has caused multiple waves of infection globally. Arizona State University (ASU), the largest four-year university in the United States, offers a uniquely diverse setting for assessing immunity within a large community. This study aimed to evaluate SARS-CoV-2 antibody seroprevalence and the effects of infection and vaccination three years into the pandemic. Methods A serosurvey was conducted at ASU from January 30 to February 3, 2023. Participants completed questionnaires about demographics, respiratory infection history, symptoms, and COVID-19 vaccination status. Blood samples were analyzed for anti-receptor binding domain (RBD) IgG and anti-nucleocapsid (NC) antibodies, offering a comprehensive view of immunity from both natural infection and vaccination. Results The seroprevalence of anti-RBD IgG antibodies was 96.2% (95% CI: 94.8%-97.2%), and 64.9% (95% CI: 61.9%-67.8%) of participants had anti-NC antibodies. Anti-RBD IgG levels correlated strongly with neutralizing antibody levels, and participants who received more vaccine doses showed higher levels of both anti-RBD IgG and neutralizing antibodies. Increasing number of exposures through vaccination and/or infection resulted in higher and long-lasting antibodies. Conclusion The high levels of anti-RBD antibodies observed reflect substantial vaccine uptake within this population. Ongoing vaccination efforts, especially as new variants emerge, are essential to maintaining protective antibody levels. These findings underscore the importance of sustained public health initiatives to support broad-based immunity and protection.