SARS CoV-2 IgG positivity among the people in Dhaka city: An observation from the post vaccine period

Immunity status after mass vaccination program against SARS CoV-2 has not been evaluated in Bangladesh. This study aims to assess the IgG response against SARS-CoV-2 among the vaccine receivers in Bangladesh. After signed consent, blood samples were tested for SARS CoV-2 IgG from volunteers between March, 21 and April, 22 using ELISA where IgG index ≥0.9 was considered as positive Among 3034 participants, IgG positivity was calculated approximately 82% for vaccine recipients; lowest (58%) during March–April, 21 which increased to 85–95% later. IgG positivity and mean index was 82% and 3.04 in vaccinated whereas 56% and 1.5 in unvaccinated cases. IgG positivity and mean index reduced with age: 90% and 2.56, 79% and 2.23, 73% and 2.13 in 18–40 y, 41–60 y, >60 y group respectively. Vaccinated with COVID-19 history showed highest IgG positivity and index (94% and 3.1) compared to vaccinated without COVID-19 history (76% and 1.6), unvaccinated with COVID-19 history (75% and 1.5) and unvaccinated without COVID-19 history (51% and 0.9). IgG positivity and index reduced as interval between IgG testing and vaccination increases. Our findings suggest a robust IgG response among the vaccine recipients. Negative correlation of IgG positivity and index with age and time necessitates continuous monitoring of immunity status.