Involvement of antibody, complement and cellular immunity in the pathogenesis of enhanced respiratory syncytial virus disease.

In 1966, infants and children in the USA were immunized with a formalin-inactivated vaccine against respiratory syncytial virus. The vaccine was immunogenic but elicited mainly nonprotective antibody. Upon exposure to respiratory syncytial virus in the community, immunized children developed severe pulmonary disease characterized by bronchoconstriction and pneumonia. Two immunized infants died as toddlers after respiratory syncytial virus infection. Exploration of the mechanisms of disease has dominated the literature for decades. In this review, the pathogenesis of enhanced respiratory disease is discussed and the characteristics of protective and pathogenic respiratory syncytial virus vaccines are examined.