Further Investigations of Live Respiratory Syncytial Virus Vaccine Administered Parenterally

SummaryFurther clinical tests were carried out of a live attenuated respiratory syncytial virus vaccine administered parenterally. Neutralization of respiratory syncytial virus by homologous human antibody was found to be a complement-dependent event and addition of guinea pig complement greatly increased antibody titers and the sensitivity of the test. Ninety-seven percent of 116 initially seronegative children developed antibody following vaccination and there was no evidence for contagious spread of the infection. Clinical reactions, if any, were mild and inconsequential. A small portion of initially seropositive persons appeared to develop antibody by booster effect and a portion of initially seronegative and seropositive persons developed detectable nasal antibody. Long-term follow-up failed to reveal any increase in severe respiratory disease in initially seronegative persons who were vaccinated. A very substantial reservoir of seronegative persons was found in the 7 to 47 month age group (35%) reve...