In Italy, from January 2021, the Ministry of Health indicated a vaccination plan against COVID for frail patients and physicians based on a three-dose scheme. However, conflicting results have been reported on which biomarkers permit immunization assessment. We used several laboratory approaches (i.e., antibodies serum levels, flow cytometry analysis, and cytokines release by stimulated cells) to investigate the immune response in a cohort of 53 family pediatricians (FPs) at different times after the vaccine. We observed that the BNT162b2-mRNA vaccine induced a significant increase of specific antibodies after the third (booster) dose; however, the antibody titer was not predictive of the risk of developing the infection in the six months following the booster dose. The antigen stimulation of PBMC cells from subjects vaccinated with the third booster jab induced the increase of the activated T cells (i.e., CD4⁺ CD154⁺); the frequency of CD4⁺ CD154⁺ TNF-α⁺ cells, as well as the TNF-α secretion, was not modified, while we observed a trend of increase of IFN-γ secretion. Interestingly, the level of CD8⁺ IFN-γ⁺ (independently from antibody titer) was significantly increased after the third dose and predicts the risk of developing the infection in the six months following the booster jab. Such results may impact also other virus vaccinations.

Background/Objectives: Chronic inflammatory diseases (CIDs) often present a preclinical phase influenced by genetic and environmental factors, including nutrition. Early dietary habits may modulate long-term health trajectories by shaping the intestinal microbiota. Previous work showed that weaning with fresh foods from the Mediterranean diet (MD) improved dietary habits and microbiota composition at 3 years of age. This study aimed to assess whether such benefits persist at 9 years. Methods: This long-term follow-up included 191 children (96 MD, 95 controls) from the original randomized cohort (ClinicalTrials.gov NCT05297357). The primary endpoint was adherence to MD (KidMed score ≥ 8). Secondary endpoints included BMI, incidence of CID, maternal dietary adherence, and intestinal microbiota composition in a subset of 36 children. Results: At 9 years, no difference was found in overall MD adherence (27.4% controls vs. 27.1% MD; p > 0.99) or BMI (17.7 vs. 18.1 kg/m²; p = 0.384). However, children from the MD group reported higher daily vegetable intake (71.9% vs. 51.6%; p = 0.005). Microbiota analyses revealed persistent differences between groups, with higher alpha diversity in the MD group. Although not statistically significant, the MD group showed lower prevalence of atopic dermatitis, allergic rhinitis, autism spectrum disorder, and ADHD. Maternal adherence to MD did not differ between groups. Conclusions: Early introduction of Mediterranean-style foods during weaning exerts lasting effects on dietary patterns and gut microbiota, with a potential protective trend against CID. While overall MD adherence converged between groups by 9 years, these findings suggest that early-life nutritional interventions may induce durable microbiome-mediated benefits and contribute to preventive strategies for chronic disease, warranting confirmation in larger, extended cohorts. Moreover, this study highlights the value of the collaboration between the Italian primary care pediatric system and the integration of the pediatric residency program, demonstrating a feasible and cost-effective methodology to generate large-scale prospective data within routine clinical practice. Larger studies and a longer follow-up period are necessary to confirm these results.