Preventing severe respiratory syncytial virus disease: passive, active immunisation and new antivirals.

In most high-income countries palivizumab prophylaxis is considered safe, efficacious and cost-effective for preventing respiratory syncytial virus (RSV) hospital admissions among specific subgroups of infants born preterm, with chronic lung disease or with congenital heart disease. Virtually all babies acquire RSV during infancy and previously healthy babies are not eligible to receive palivizumab. Emerging evidence suggests some benefit of palivizumab use in reducing recurrent wheeze among infants born preterm. Better longitudinal studies are needed to examine its clinical and cost-effectiveness on recurrent and chronic respiratory illness and associated healthcare burden on resources in the community and hospitals. Since 99% of child deaths attributed to RSV occur in resource poor countries where expensive prophylaxis is not available or affordable, palivizumab has limited potential to impact on the current global burden of RSV lower respiratory tract infection (LRTI). A range of candidate vaccines for active immunisation against RSV are now in clinical trials. Two promising new antivirals are also currently in phase I/II trials to test their effectiveness in preventing severe RSV LRTI. These agents may be effective in preventing severe disease and phase III studies are in development. In the absence of effective active immunisation against RSV infection, population level approaches to prevent severe RSV LRTI should continue to focus on reducing prenatal and environmental risk factors including prematurity, smoking and improving hygiene practices.