Background: Faecal calprotectin has been proposed as a sensitive marker for gastrointestinal inflammation in children and adults. High levels have been reported in healthy newborns and during the first months of life; the effect of the kind of feeding on the calprotectin concentration in stools is controversial. Objective: To evaluate faecal calprotectin values in healthy, exclusively breast-fed (BF) or formula-fed (FF) infants. Methods: Stool samples were obtained from 74 healthy infants (39 exclusively BF and 35 exclusively FF) with a median age of 51 days (range 13–90). Exclusion criteria were acute infections and treatment with anti-inflammatory drugs. Stool samples were stored at –20°C until they were analysed, and the faecal calprotectin concentration was detected using a commercial quantitative enzyme-linked immunoassay (Calprest; Eurospital SpA, Trieste, Italy). Results: The median faecal calprotectin concentration was significantly higher in BF infants (555.00 µg/g, range 122.5–2,000.0 µg/g) than in FF ones (206.60 µg/g, range 31.2–797.6 µg/g) (p < 0.001). We observed a significantly higher median stool frequency in BF infants than in FF ones (p < 0.001), but multiple regression analysis (independent variables: kind of feeding and stool frequency; dependent variable: calprotectin) showed a significant coefficient for the kind of feeding, but not for stool frequency (p = 0.937). Conclusions: Our findings show that the kind of feeding influences the faecal calprotectin concentration, with higher values in healthy exclusively BF infants than in FF ones. Our study does not allow us to clearly identify the reason for our finding; this could be due to hormones (such as ghrelin and leptin), cytokines and other immunostimulating and growth factors (such as epidermal growth factor and granulocyte colony-stimulating factor) in human milk, which contribute to the development of the gastrointestinal immune system. Further investigations are needed to better clarify the mechanism underlying the relationship between feeding and faecal calprotectin levels in young infants.

The restrictive measures adopted worldwide against SARS-CoV-2 produced a drastic reduction in respiratory pathogens, including RSV, but a dramatic rebound was thereafter reported. In this multicenter retrospective observational study in 15 Pediatric Emergency Departments, all children <3 years old with RSV infection admitted between 1 September and 31 December 2021 were included and compared to those admitted in the same period of 2020 and 2019. The primary aim was to evaluate RSV epidemiology during and after the COVID-19 pandemic peak. The secondary aims were to evaluate the clinical features of children with RSV infection. Overall, 1015 children were enrolled: 100 in 2019, 3 in 2020 and 912 in 2021. In 2019, the peak was recorded in December, and in 2021, it was recorded in November. Comparing 2019 to 2021, in 2021 the median age was significantly higher and the age group 2–3 years was more affected. Admissions were significantly higher in 2021 than in 2020 and 2019, and the per-year hospitalization rate was lower in 2021 (84% vs. 93% in 2019), while the duration of admissions was similar. No difference was found in severity between 2019–2020–2021. In conclusion, after the COVID-19 pandemic, an increase in RSV cases in 2021 exceeding the median seasonal peak was detected, with the involvement of older children, while no difference was found in severity.