The Role of Immunoprophylaxis in the Reduction of Disease Attributable to Respiratory Syncytial Virus

Abstract

Respiratory syncytial virus (RSV) is an RNA virus that infects human respiratory epithelial cells and causes annual outbreaks of respiratory tract disease among infants and young children, as well as recurrent infections throughout life. Annual outbreaks of RSV disease are attributable to first-time infection in susceptible infants, reinfection in children and adults with waning or incomplete immunity, and infection by viral genotypes with sufficient antigenic variation to avoid innate and acquired immunity. In industrialized countries, few infectious diseases have a greater effect on the health of young children than does lower respiratory tract disease caused by RSV. By 2 years of age, almost all children will experience an RSV infection, and ∼50% will be infected twice.1 Results from the New Vaccine Surveillance Network (a prospective, population-based surveillance program sponsored by the Centers for Disease Control and Prevention [CDC]) define the burden of RSV disease in children younger than 5 years of age.2 An estimated 2 million children require medical care because of RSV infection, and ∼57500 children younger than 5 years are hospitalized annually. The major burden of RSV disease occurs among previously healthy infants and children whose susceptibility to severe RSV illness cannot be predicted by risk factors. Protection against RSV infection is mediated by serum antibody, secretory antibody, cytotoxic T lymphocytes, and innate immune responses. A vaccine offers the greatest promise for control of RSV disease, but vaccine development has been slowed by concerns about safety (enhancement of naturally occurring disease), the limited ability of infants to mount an immune response to RSV glycoprotein antigens, and the presence of maternal neutralizing antibody, which may attenuate an active immune response. Passive immunization with either a hyperimmune globulin or a monoclonal antibody preparation has been demonstrated in randomized, placebo-controlled trials to reduce the risk of hospitalization caused by … Address correspondence to H. Cody Meissner, MD, Tufts Medical Center, 750 Washington St, Boston, MA 02111. E-mail: cmeissner{at}tuftsmedicalcenter.org