Do COVID-19 Antibodies Provide Long-Term Protection?

Introduction: Post severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, an immune response is generated among healthy, immunocompetent individuals with immunoglobulins (IgG and IgM) antibodies. IgM rises earlier than IgG, indicating a recent infection. However, a detailed analysis is required to assess long-term immune reactions induced by antibodies. Method and Materials: The study was conducted at a tertiary care hospital in Pakistan from June 2020 to October 2020 where serum samples were collected from patients. The samples were obtained by phlebotomy for antibody testing. All the reactive patients were followed up after 60 days of initial testing. Results: A total of 728 patients participated in the study, of which 79​ (10.8%) were seropositive at baseline. Seventy-two (91.1%) participants came back for follow-up after 60 days (two months) and were included in the final analysis. Among the 72 participants, 35 (48.6%) exhibited symptoms of coronavirus disease 2019 (COVID-19) infection and 37 (51.4%) were asymptomatic. After 60 days, 37 (including 20 symptomatic and 17 asymptomatic) participants were still seropositive for SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) test. Mean change in percentage from seropositive to seronegative was more in asymptomatic compared to symptomatic patients (54.0% vs. 42.8%). Conclusion: In this study, humoral immunity against SARS-CoV-2 is not long-lasting among individuals with mild signs and symptoms. Care should be taken while implicating that antibodies can provide long term protection against SARS-CoV-2. Further large-scale studies are needed.