The purpose of this study was to see if a 3-month therapy with Lactobacillus rhamnosus GG (LGG) might change immune system functioning in children and adolescents with type 1 diabetes (T1D), resulting in a stronger immunological response to an injectable quadrivalent inactivated influenza vaccine (QIV). A total of 87 juvenile T1D patients were screened, with 34 in the Probiotic group and 30 in the Control group agreeing to be vaccinated with QIV and completing the research. The immunogenicity and safety of vaccines, as well as the inflammatory cytokine response, were investigated. The results revealed that QIV was immunogenic and safe in juvenile T1D patients, and that three months of pre-administration of LGG did not significantly alter QIV humoral immunity. The combination of QIV and LGG suppressed inflammatory responses in activated PBMCs from juvenile T1D patients while not suppressing the generation of seroprotective antibodies.

In conclusion, QIV has a favorable safety profile and is linked with sufficient immunogenicity in children and adolescents with T1D. Despite the fact that a systematic dose of LGG did not increase humoral responses to an influenza vaccination, the probiotic did have significant anti-inflammatory benefits.