Immunogenicity and safety of SARS-CoV-2 mRNA vaccines in a cohort of patients with type 1 diabetes

Patients with type 1 diabetes (T1D) may develop severe outcomes during COVID-19 disease, but their ability to generate an immune response against the SARS-CoV-2 messenger RNA (mRNA) vaccines remains to be established. Here we evaluated the safety, immunogenicity and glycometabolic effects of the SARS-CoV-2 mRNA vaccines in patients with T1D. A total of 375 patients, 326 with T1D and 49 non-diabetics, who received two doses of the SARS-CoV-2 mRNA vaccines (mRNA-1273, BNT162b2) between March and April 2021 at the ASST FBF-Sacco Milan, Italy, were included in this monocentric observational study (NCT04905823). Local and systemic adverse events were reported in both groups after SARS-CoV-2 mRNA vaccination without statistical differences between them. While both T1D patients and non-diabetic subjects exhibited a parallel increase in anti-SARS-CoV-2S titers after vaccination, the vast majority of T1D patients (70% and 78% respectively) did not show any increase in the SARS-CoV-2-specific cytotoxic response as compared to the robust increase observed in all non-diabetic subjects. A reduced secretion of the T cell-related cytokines IL-2 and TNF-alpha in vaccinated patients with T1D was also observed. No glycometabolic alterations were evident in patients with T1D using continuous glucose monitoring during follow-up. Administration of the SARS-CoV-2 mRNA vaccine is associated with an impaired cellular SARS-CoV-2-specific cytotoxic immune response in T1D patients.