Seroconversion and side effects after COVID vaccination among persons with type 2 diabetes in urban, rural, and tribal areas in Kerala, India.

Background: Persons with type 2 diabetes mellitus (T2DM) are at high-risk for COVID-19 infection and are a priority group for vaccination.

Objectives: The objective of this study is to estimate the seroconversion and determine the side effects after COVID-19 vaccination among persons with T2DM in urban, rural, and tribal areas in Kerala.

Methods: A cross-sectional study was conducted in urban, rural, and tribal field practice areas of a medical college in Central Kerala, among 396 persons with T2DM. The participants were selected by simple random sampling from the 200-250 diabetic patients visiting each health center. Qualitative and quantitative estimation of antibodies were done by WANTAI Ab enzyme-linked immunosorbent assay kit and Abbott SARS COV-2 IgG Quantitative assay, respectively.

Results: The mean age of the respondents was 59.40 ± 12.25 years. A majority (65.5%) had received both doses of vaccine. About half (51.5%) experienced side effects after vaccination. Antibodies (IgG or IgM) were detected in 93.2% (95% confidence interval [CI] 90.2, 95.5) of participants. Those with a duration of diabetes ≥5 years, with a single dose of vaccine, were five times (adjusted odds ratio [aOR] - 5.23,95% CI 1.86, 14.66) and four times (aOR - 4.11, 95% CI 1.66, 10.13) more likely, respectively, to be seronegative. Those who took medication for diabetes were protected against a no antibody (aOR - 0.05, 95% CI 0.02, 0.148) response. The median antibody titer in a subset (150) of participants was 365.2 (90-1587) AU/ml. Past COVID infection was an independent determinant of high IgG titers (aOR - 4.95, 95% CI 1.50, 16.36).

Conclusion: Reinforcing the importance of vaccination particularly among those with longer duration of diabetes is imperative.