Impaired antibody responses to heterologous ChAdOx1 nCoV-19 and BNT162b2 vaccination in individuals with type 2 diabetes.

The COVID-19 pandemic has caused many deaths worldwide, especially in patients with type 2 diabetes mellitus (DM). Owing to the association of type 2 DM with immune dysfunction, we evaluated the impact of DM on the humoral immune responses induced by inactivated (Sinovac, SV), viral vector (ChAdOx1 nCoV-19, Az) and mRNA (BNT162b2, BNT) vaccines, compared with those in non-DM individuals. The levels of anti-spike (S) and neutralizing antibodies (nAbs) against the S1 domain/receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before and after COVID-19 vaccination were determined. The immune response in non-DM individuals heterologously immunized with the Az-BNT regimen was more robust than that in those immunized with other regimens. Notably, individuals with type 2 DM presented reduced anti-S antibody levels following vaccination with the Az-BNT regimen at 30 and 90 days post-vaccination. Furthermore, a rapid decline in nAb levels in DM individuals was noted on day 90 post-boost for all regimens. Thus, a shorter interval between boosters might be necessary for DM individuals. These findings could inform the selection of optimal vaccination protocols for individuals with or without DM and contribute to the development of an efficacious COVID-19 vaccine for individuals with underlying health conditions, particularly DM.