Risk of Transmission of Vaccine-Strain Rotavirus in a Neonatal Intensive Care Unit That Routinely Vaccinates

Many neonatal intensive care units (NICUs) do not give rotavirus vaccines to inpatients due to a theoretical risk of horizontal transmission of vaccine strains. We aimed to determine incidence and clinical significance of vaccine-strain transmission to unvaccinated infants in a NICU that routinely administers pentavalent rotavirus vaccine (RV5). This prospective cohort study included all patients admitted to a 100-bed NICU for 1 year. Stool specimens were collected weekly; real-time quantitative reverse-transcription polymerase chain reaction was used to detect any RV5 strain. Incidence of transmission to unvaccinated infants was calculated assuming each unvaccinated patient's stool contributed 1 patient-day at risk for transmission. Investigations and geospatial analyses were conducted for suspected transmission events. Of 1238 infants admitted, 560 (45%) were premature and 322 (26%) had gastrointestinal pathology. During observation, 226 RV5 doses were administered. Overall, 3448 stool samples were tested, including 2252 from 686 unvaccinated patients. Most (681, 99.3%) unvaccinated patients never tested positive for RV5 strain. Five (