Priorities for developing respiratory syncytial virus (RSV) vaccines in different target populations

Respiratory syncytial virus (RSV) is a major cause of severe respiratory tract infection worldwide. but tThere is a monoclonal antibody, palivizumab, which can be used for prophylaxis, butis no licensed vaccine or clinically effective antiviral therapy. The development of an effective vaccine has been hampered over the last 50 years by a medical disastersignificant difficulties in the 1960s in which a formalin-inactivated vaccine led to increased severity of RSV disease following acquisition of the virus in the RSV season after vaccination. However, renewed efforts to develop a vaccine have resulted in up to 445 candidate vaccines and monoclonal antibodies now being in pre-clinical or clinical development (as of December 2018April 2019). The target populations for effective vaccination are varied and include neonates, young children, pregnant women and older adults. The reasons for susceptibility to infection in each of these groups may be different and could therefore require different vaccine types for induction of protective responses, adding a further challenge for vaccine development. Here we review the current knowledge of vaccine development for these target populations, and we propose a view of the priorities for RSV vaccines and their rationale