mRNA (BNT162b2) and Inactivated (CoronaVac) COVID-19 Vaccination and Risk of Adverse Events and Acute Diabetic Complications in Patients with Type 2 Diabetes Mellitus: A Population-Based Study

Introduction In Hong Kong, CoronaVac and BNT162b2 have been approved for emergency use owing to the coronavirus disease 2019 (COVID-19) pandemic. Reactions towards the vaccine and the risk of post-vaccination adverse events may be different between recipients with and without type 2 diabetes mellitus (T2DM). Objective The aim of this study was to evaluate the risk of adverse events of special interest (AESI) and acute diabetic complications in the T2DM population after COVID-19 vaccination in Hong Kong. Research Design and Methods Self-controlled case-series analysis was conducted. Patients with T2DM who received at least one dose of BNT162b2 or CoronaVac between 23 February 2021 and 31 January 2022 from electronic health records in Hong Kong were included. The incidence rates of 29 AESIs and acute diabetic complications (any of severe hypoglycemia, diabetic ketoacidosis or hyperosmolar hyperglycemic syndrome) requiring hospitalization within 21 days after the first or second dose of vaccination were reported. The risks of these outcomes were evaluated using conditional Poisson regression. Results Among 141,224 BNT162b2 recipients and 209,739 CoronaVac recipients with T2DM, the incidence per 100,000 doses and incidence per 100,000 person-years of individual AESIs and acute diabetic complications ranged from 0 to 24.4 and 0 to 438.6 in BNT162b2 group, and 0 to 19.5 and 0 to 351.6 in CoronaVac group. We did not observe any significantly increased risk of individual AESIs or acute diabetic complications after first or second doses of BNT162b2 or CoronaVac vaccine. Subgroup analysis based on HbA1c < 7% and ≥ 7% also did not show significantly excess risk after vaccination. Conclusions Patients with T2DM do not appear to have higher risks of AESI and acute diabetic complications after BNT162b2 or CoronaVac vaccination. Moreover, given the low incidence of AESIs and acute diabetic complications after vaccination, the absolute risk increment was likely minimal.