Abstract

Respiratory syncytial virus (RSV) causes infection throughout life, with infants, adults who are severely immunocompromised, and the elderly at special risk of developing lower respiratory tract disease, hospitalisation, and death. The burden of severe disease in the elderly is comparable to seasonal influenza, and there remains no effective anti-viral drugs or vaccine for any target population. The development of a vaccine to confer immunity against severe disease is a major global health priority. A multitude of safe and immunogenic vaccine candidates have failed to induce the protective immunity needed for licensure, and in recent years this has included the largest clinical trials of RSV vaccines in history. The obstacles to vaccine development in elderly populations include an incomplete understanding of the immune responses needed for protection, the effect of aging on induction and maintenance of immunity (natural and vaccine induced immunity), and the high rate of co-morbid disease in older adults. Recent advances in structural biology, new biological platforms for antigen delivery, and insights from experimental challenge models mark the latest developments in over 50 years of research. This continues to be an active and evolving field of scientific discovery with renewed hope for a vaccine in the future.