Universal mass vaccination against rotavirus: Indirect effects on rotavirus infections in neonates and unvaccinated young infants not eligible for vaccination

Abstract

Background. Rotavirus (RV)-associated infections account for high numbers of hospitalizations in neonates and young infants. Universal mass vaccination (UMV) has been shown to prevent the burden of disease in vaccinated children. Methods. The present study investigated the long-term effects of UMV on RV-associated hospitalizations in children with particular focus on neonates and young infants (?42 days old) not eligible for vaccination. Ten years of Austrian surveillance data were compared, including 10 960 laboratory-confirmed RV cases before (prevaccination period [PreVP]) and after (postvaccination period [PostVP]) introduction of UMV. Results. A postvaccination decrease in hospitalized community-acquired RV infections by 89.3% was seen in all age groups, including unvaccinated neonates and young infants. Of the latter, 27.6% had a nosocomial RV infection in PreVP, and 19.3% in PostVP. Overall, the proportion of nosocomial RV infections increased from 5.5% in PreVP to 13.0% in PostVP. Breakthrough infections, usually after incomplete RV vaccination, could be identified in 6.2% of patients. Conclusions. Unvaccinated neonates and infants ?42 days old may indirectly benefit from UMV by reduction of RV infections. Breakthrough infections underline the importance of early and complete protection by the vaccine. In older patients, heightened awareness of nosocomial RV infections is warranted. Identification of RV reservoirs is also needed.