Respiratory syncytial virus vaccines: an update on those in the immediate pipeline.

Respiratory syncytial virus (RSV) is among the most common causes of lower respiratory tract infection among infants and the elderly worldwide. Despite its long history, no licensed vaccine is available. Recently, advances in the knowledge of RSV biology and pathology as well as the development of new techniques to generate vaccine candidates have increased the number of promising vaccines. The aim of this review is to analyze RSV characteristics, to consider the history of RSV vaccines and to discuss RSV vaccines currently in development. Among the candidates in clinical trials, nanoparticle and subunit vaccines seem to be the most promising for pregnant women and the elderly, whereas live-attenuated or vector-based vaccines appear to be optimal for the pediatric population.