Figure 2.

Anti-influenza and anti-COVID-19 vaccine-specific antibody production in healthy and type 2 diabetes mellitus (T2D) vaccine recipients. Levels of binding class G immunoglobulins recognizing SARS-CoV-2 trimeric spike protein (anti-SARS-CoV-2 S IgG; expressed as BAU/mL) (A) and specific anti-influenza (Flu) antibodies against all the vaccine antigen components included in the Flucelvax Quadrivalent flu vaccine used in the 2021–2022 season (A/Wisconsin, A/Cambodia, B/Phuket and B/Washington; expressed as hemagglutination inhibition, HAI, titers) (B–E) were measured in “CoV_only” group (in grey), “Flu_beforeCoV” (in light blue) as well as “Flu_plusCoV” groups (in blue for healthy subjects, HS; in petrol green for T2D individuals). Serum samples were analyzed before (day 0, d0) and 30 days (d30) after the third booster dose of COVID-19 mRNA vaccine in the presence or absence of flu vaccination. Only for “Flu_beforeCoV” subjects, sera were tested before (day 0, d0) quadrivalent flu vaccine, as well before (day 30, d30) and 30 days after the third booster dose of COVID-19 mRNA vaccine (d30 + 30). p-values calculated by one-way ANOVA test were assigned as follows: * ≤ 0.05; ** ≤ 0.01; *** ≤ 0.001, **** ≤ 0.0001.