Humoral Immune Durability of Anti-SARS-CoV-2 Antibodies in Southern Iran: A Population-Based Survey Study

Background: To promote mitigation strategies and public health response, this study aimed to evaluate the population-based seroprevalence of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in Hormozgan province. Materials and Methods: The study was conducted within 10 districts of Hormozgan province with 1325 participants for three months by considering three-month successive follow-ups to evaluate the durability of humoral immunity. The participants completed the questionnaire, and blood samples were taken followed by immunoassay SARS-CoV-2 ELISA testing. Results: In general, 717 (54.1%) males and 596 (45.9%) females participated in this study. In phase one, 147 (11.1%) and 182 (14.7%) tested positive for immunoglobulin M (IgM) and IgG, respectively. Upon three months, 13.8% and 17.8% tested positive for IgG and at least for one of the antibodies. Based on the results, 606 (45.7%) cases reported no symptoms while 673 (50.8%) of them reflected at least one. Among 798 (60.2%) participants, the most common symptoms were headache (n = 244, 18.4%), sore throat (n = 186, 14.0%), weakness (n = 150, 11.3%), muscular pain (n = 139, 10.5%), and sputum cough (n = 134, 10.1%). The odds of the antibodies in females was 1.37 (95% CI: 1.03, 1.82, P = 0.03). In phase 2, 43 (5.3%) participants persisted positive for IgG while 559 (73%) tested negative for IgG. Finally, 20% of the suffered participants tested positive for IgG until nine months. Conclusion: Although IgG antibodies decreased in the first six months, their titers persisted stable for nine months. It seems our population has not reached a desirable level of protection. It is stressed that mass vaccination is needed to prevent future epidemic waves.