Respiratory Syncytial Virus (RSV) is an increasingly recognized cause of serious disease in older adults. RSV causes excess morbidity and mortality in older persons residing in nursing homes and in the community. The study of RSV in adults has been hampered by the lack of sensitive methods for the diagnosis of acute infections. Such tools are needed to better understand the epidemiology and immunology of RSV in adults. The immune status of older adults has begun to be explored and preliminary data indicates that low serum neutralizing antibody may predispose to symptomatic RSV infection and that a greater diversity of antibody titres may be seen in the elderly compared to young adults. PFP-2, a candidate RSV subunit vaccine, has been evaluated in healthy and institutionalized elderly and been found to be safe and immunogenic.