Safety of Rotavirus Vaccination in Preterm Infants Admitted in Neonatal Intensive Care Units in Sicily, Italy: A Multicenter Observational Study

Rotavirus (RV) is among the most common vaccine-preventable diseases in children under five years of age. Despite the severity of rotavirus pathology in early childhood, rotavirus vaccination for children admitted to the neonatal intensive care unit (NICU), who are often born preterm and with various previous illnesses, is not performed. This multicenter, 3-year project aims to evaluate the safety of RV vaccine administration within the six main neonatal intensive care units of the Sicilian Region to preterm infants. Methods: Monovalent live attenuated anti-RV vaccination (RV1) was administered from April 2018 to December 2019 to preterm infants with gestational age ≥ 28 weeks. Vaccine administrations were performed in both inpatient and outpatient hospital settings as a post-discharge follow-up (NICU setting) starting at 6 weeks of age according to the official immunization schedule. Any adverse events (expected, unexpected, and serious) were monitored from vaccine administration up to 14 days (first assessment) and 28 days (second assessment) after each of the two scheduled vaccine doses. Results: At the end of December 2019, 449 preterm infants were vaccinated with both doses of rotavirus vaccine within the six participating Sicilian NICUs. Mean gestational age in weeks was 33.1 (±3.8 SD) and the first dose of RV vaccine was administered at 55 days (±12.9 SD) on average. The mean weight at the first dose was 3388 (SD ± 903) grams. Only 0.6% and 0.2% of infants reported abdominal colic and fever above 38.5 °C in the 14 days after the first dose, respectively. Overall, 1.9% EAEs were observed at 14 days and 0.4% at 28 days after the first/second dose administration. Conclusions: Data obtained from this study confirm the safety of the monovalent rotavirus vaccine even in preterm infants with gestational age ≥ 28 weeks, presenting an opportunity to improve the vaccination offer both in Sicily and in Italy by protecting the most fragile infants who are more at risk of contracting severe rotavirus gastroenteritis and nosocomial RV infection.