Background: The adaptive immune response is a crucial component of the protective immunity against SARS-CoV-2, generated after infection or vaccination. Methods: We studied antibody titers, neutralizing antibodies and cellular immune responses to four different COVID-19 vaccines, namely Pfizer-BioNTech, Moderna Spikevax, AstraZeneca and Sinopharm vaccines in the Bangladeshi population (n = 1780). Results: mRNA vaccines Moderna (14,655 ± 11.3) and Pfizer (13,772 ± 11.5) elicited significantly higher anti-Spike (S) antibody titers compared to the Adenovector vaccine AstraZeneca (2443 ± 12.8) and inactivated vaccine Sinopharm (1150 ± 11.2). SARS-CoV-2-specific neutralizing antibodies as well as IFN-γ-secreting lymphocytes were more abundant in Pfizer and Moderna vaccine recipients compared to AstraZeneca and Sinopharm vaccine recipients. Participants previously infected with SARS-CoV-2 exhibited higher post-vaccine immune responses (S-specific and neutralizing antibodies, IFN-γ-secreting cells) compared to uninfected participants. Memory B (BMEM), total CD8+T, CD4+ central memory (CD4+CM) and T-regulatory (TREG) cells were more numerous in AstraZeneca vaccine recipients compared to other vaccine recipients. Plasmablasts, B-regulatory (BREG) and CD4+ effector (CD4+EFF) cells were more numerous in mRNA vaccine recipients. Conclusions: mRNA vaccines generated a higher antibody response, while a differential cellular response was observed for different vaccine types, suggesting that both cellular and humoral responses are important in immune monitoring of different types of vaccines.

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The purpose of this study was to determine the seropositivity of circulating viral pathogens and their association with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seropositivity. In a cross-sectional design, inhabitants (aged 10–60 years) of the slum and surrounding non-slum areas of Dhaka and Chattogram Metropolitan cities in Bangladesh were enrolled from October 2020 to February 2021. Antibodies to SARS-CoV-2, influenza B, parainfluenza, respiratory syncytial virus (RSV), human coronavirus HKU1 (HCoV-HKU1), dengue and chikungunya viruses were determined in plasma. The association of SARS-CoV-2 seropositivity with seropositivity to other viruses was assessed using the multi-variate logistic regression model. Seroprevalence of SARS-CoV-2, influenza B, RSV, dengue, chikungunya, HCoV-HKU1 and the parainfluenza virus were 68.3%, 98%, 50.0%, 16.5%, 15.5%, 3.36% and 0.0%, respectively. Individuals seropositive for RSV had lower odds (OR = 0.60; 95% CI= 0.49, 0.73) of SARS-CoV-2 seropositivity compared to RSV-seronegative individuals. Conversely, higher odds of SARS-CoV-2 seropositivity were observed in participants seropositive for dengue (OR= 1.73; 95% CI = 1.14, 2.66, only in slum) or chikungunya (OR = 1.48; 95% CI = 1.11, 1.95) compared to their seronegative counterparts. The study findings indicated that exposure to vector-borne virus dengue or chikungunya enhance, while antibodies to respiratory virus RSV decrease, the serological response to SARS-CoV-2.