Rotavirus Vaccine Administration in Preterm and Medically Fragile Infants Admitted to Neonatal Intensive Care Units: Second Phase Enrollments and Final Results of a Multicenter Observational Study Conducted in Sicily, Italy

Rotavirus disease is the world's leading cause of severe gastroenteritis and mortality in children up to 5 years of age. Premature infants are more vulnerable to rotavirus gastroenteritis (RVGE) and its complications. International authorities strongly recommend vaccination because of the consistent reduction in infections, hospitalizations, deaths, and related costs.

The objective of the present study was to evaluate the safety of anti-rotavirus vaccination in premature infants admitted and vaccinated in the main Sicilian Neonatal Intensive Care Units (NICUs) during the pandemic period.

The human monovalent rotavirus vaccination (RV1) was administered to preterm infants of gestational age ≥28 weeks in the main Sicilian NICUs from January 2020 to December 2022, as a prolongation of a similar study conducted from April 2018 to December 2019. Rotavirus vaccinations were provided both to hospitalized infants and to those returning for post-discharge follow-up, beginning at six weeks of age according to the official immunization schedule. All potential adverse events-whether expected, unexpected, or serious-were recorded from the day of vaccination through 14 days (first follow-up) and 28 days (second follow-up) after each of the two scheduled doses.

A total of 355 preterm infants were fully vaccinated with RV in four Sicilian NICUs. The mean gestational age of newborns was 33.2 weeks (±2.7), 53% of whom were male. Vaccination was performed on average at 7 weeks of age (±2.1), and the mean weight at the time of vaccination was 3439 g (SD ± 745.2). No expected/unexpected or serious adverse events were observed either within the 14-day or within the 28-day period after administration of both two doses.

Data confirm that vaccination in preterm infants ≥28 weeks gestational age is safe. The prolongation of this Public Health strategy, strongly recommended by the Sicilian Health Department during the pandemic period that also generally has led to a reduction of vaccination adherence and acceptance of pediatric vaccination, demonstrates the importance of multidisciplinary collaboration with neonatologists and pediatricians to continue promoting in-hospital vaccinations for fragile subjects.