Study of antibody titres after measles vaccination: fever within 7 days of vaccination and efficacy of booster doses.

We investigated seroconversion rates in febrile children after measles vaccination. Among 6364 vaccinees, 501 children had a temperature of 37.5 degrees C or higher within 7 days of vaccination. The seroconversion rate assessed by a haemagglutination-inhibition assay was 76.6% in 501 febrile children but 95.2% in 84 afebrile controls. Measles vaccination has been reported to provide immunity in at least 95% of cases. The number of patients infected with measles has dramatically decreased since the introduction of measles vaccination. However, problems remain, including primary vaccine failure (PVF), failure to develop immunity after vaccination, and secondary vaccine failure (SVF), that is, the development of infection because of waning antibodies after vaccination. In this study, we investigated the effect of febrile upper respiratory tract infection (URTI) after vaccination and found a lower rate of seroconversion to measles and a lower mean antibody titre in those who developed a fever within 7 days of measles vaccination.