Measles Outbreak in a Fully Immunized Secondary-School Population

Abstract

An outbreak of measles occurred among adolescents in Corpus Christi, Texas, in the spring of 1985, even though vaccination requirements for school attendance had been thoroughly enforced. Serum samples from 1806 students at two secondary schools were obtained eight days after the onset of the first case. Only 4.1 percent of these students (74 of 1806) lacked detectable antibody to measles according to enzyme-linked immunosorbent assay, and more than 99 percent had records of vaccination with live measles vaccine. Stratified analysis showed that the number of doses of vaccine received was the most important predictor of antibody response. Ninety-five percent confidence intervals of seronegative rates were 0 to 3.3 percent for students who had received two prior doses of vaccine, as compared with 3.6 to 6.8 percent for students who had received only a single dose. After the survey, none of the 1732 seropositive students contracted measles. Fourteen of 74 seronegative students, all of whom had been vaccinated, contracted measles. In addition, three seronegative students seroconverted without experiencing any symptoms. We conclude that outbreaks of measles can occur in secondary schools, even when more than 99 percent of the students have been vaccinated and more than 95 percent are immune.

The seroepidemiology of measles in Western Europe

“…This difference is probably explained by lower antibody titre after vaccination (or more rapid antibody loss) than after natural infection [24]. A cohort study in Finland demonstrated that vaccine induced measles antibodies declined more rapidly in the absence of natural boosting than expected [25].…”

Successful control of a school based measles outbreak by immunization

“…In outbreaks occurring between 1985 and 1986, 60 % of cases were due to vaccine failure, with vaccination prior to 12 or 15 months of age and vaccinations before 1979 (when the vaccine was less heat stable), being identified as risk factors [4,7,9]. There was, by contrast, no evidence of vaccine failure in our outbreak.…”

“…Of 1408 questionnaires 1174 (83%) were returned ( 4 cases the history was unknown, and in a further 4 cases parents gave a history of vaccination which was not confirmed by the records. There were no cases with documented evidence of vaccination and a negative parental history.…”

“…Such extra-curricular events including school dances are referred to in an outbreak in Texas [4]. School buses were identified as a risk factor on the basis of the dates of onset of cases in an outbreak in upstate New York [18].…”

“…Localized outbreaks of measles in older children are an increasing problem [1][2][3] in the UK, and continue to pose problems in the USA despite high levels of vaccination coverage [4][5][6][7]. Since the introduction of measles vaccine in the UK in 1968 and measles, mumps, rubella (MMR) vaccination in 1988, the number of cases of measles reported annually has fallen from 80999 in 1986 [8] to 10264 in 1992 [1] but there has been a shift in the age distribution of notified cases.…”