Antibody responses after Oxford AstraZeneca (Covishield) vaccine among healthcare workers in Dhaka Medical College, Dhaka, Bangladesh

Oxford AstraZeneca (Covishield) vaccine is the 1st vaccine administered in Bangladesh to prevent the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The antibody response after 1st and 2nd doses of this vaccine was assessed in health care workers of Dhaka Medical College Hospital, Bangladesh. Blood sample was collected from healthcare workers (teachers, clinicians and medical staff) after 28 days of 1st vaccination and 14 days after 2nd vaccination. Quantitative post-vaccination antibody responses were measured using the chemiluminescent immunoassay, ADVIA Centaur (Siemens, Munich, Germany) SARS-CoV-2 IgG (COV2G) assay (output index was 1.00). Vaccine related antibody was found in 126 (41%) participants after 1st dose of AstraZeneca vaccine. After 2nd dose of vaccine, reactive level of antibody was found in 172 (93%) participants. Antibody responses were significantly higher in previously infected participants compared to participants who had no history of previous COVID-19 after 1st dose (51.92+or-50.85 vs 23.67+or-41.07, p=0.001) as well as 2nd dose of vaccine (64.12+or-97.76 vs 35.04+or-64.84, p=0.001). No difference in antibody response was observed among participants with or without comorbidities. Oxford AstraZeneca Covishield vaccine induces a strong immune response after two doses of vaccination.