Robust  cellular immune responses following two doses of BNT162b2 mRNA vaccine against  SARS-CoV-2 in type 2 diabetic subjects: A longitudinal study in Bangladesh            

Abstract

Background: Diabetes, one of the most common comorbidities of COVID-19, is prioritized for SARS-CoV-2 vaccination. To evaluate the T-cell mediated immune responses, this study assessed and compared IFN-γ and IL-2 secreting PBMCs against the SARS-CoV-2 BNT162b2 mRNA vaccine in individuals with type 2 diabetes mellitus. Methods: In this longitudinal study, 19 known cases of type 2 diabetes and 16 healthy controls were included through purposive sampling and were regularly sampled before 1 dose, 4 weeks after 1 dose and 2-4 weeks after 2dose of vaccination. Ex-vivo ELISpot assays for IFN-γ and IL-2 were done using isolated PBMCs. HbA1c status was determined by an automated analyzer before 1 dose and SARS-CoV-2 spike-specific IgG antibody were assessed by CLIA 4 weeks after 1dose. A p -value <0.05 was considered significant. Results: All participants were seroconverted after 1 dose and showed a robust rise of IFN-γ and IL-2 secreting PBMCs counts in type 2 diabetic participants irrespective of hypertension, gender and age after two doses of vaccination. However, IFN-γ secreting PBMCs counts were significantly lower in type 2 diabetic group than healthy control group after 1 dose. Substantial negative correlations of HbA1c (%) to IFN-γ secreting PBMCs counts after 2 dose were also found in this study. Conclusion: Although type 2 diabetic participants had a lower response initially, BNT162b2 mRNA vaccine overall induces a robust T-cell mediated immune response.