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Estimation of measles vaccine coverage needed to prevent transmission in schools
Author(s) -
Mori Nobuo,
Ohkusa Yasushi,
Ohyama Takaaki,
TanakaTaya Keiko,
Taniguchi Kiyosu,
Kobayashi John M.,
Doy Mikio,
Okabe Nobuhiko
Publication year - 2008
Publication title -
pediatrics international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.49
H-Index - 63
eISSN - 1442-200X
pISSN - 1328-8067
DOI - 10.1111/j.1442-200x.2008.02592.x
Subject(s) - medicine , outbreak , measles , transmission (telecommunications) , confidence interval , immunization , pediatrics , measles vaccine , demography , vaccination , virology , immunology , antibody , electrical engineering , sociology , engineering
Background: The aim of the present study was to produce the first estimation in Japan of the basic reproduction number (R 0 ) and the minimum level of vaccine coverage needed to prevent measles outbreaks (P c ). Methods: A questionnaire survey was conducted during two measles outbreaks among 12–15‐year‐old middle school students in one prefecture in spring, from the end of February to the beginning of May 2002, and a stochastic mathematical model was constructed to calculate vaccine effectiveness (VE) and the basic reproduction number (R 0 ). P c was calculated from R 0 and VE. Results: In outbreak 1 (school A), 62 (94%) of 66 patients responded to the questionnaire. Of a total of 601 students, 534 (88.9%) responded. Of these, 82.6% (441/534) had previously received measles vaccine. In outbreak 2 (school B), 20 (99%) of 21 patients responded. Of a total of 375 students, 373 (99.5%) responded. Of these, 317 (85.0%) received measles immunization. Mathematical analysis was as follows: in outbreak 1 R 0 was 7.40 (95% confidence interval [CI]: 7.36–7.44) and VE was 76.55% (95%CI: 53.24–87.54). In outbreak 2, R 0 was 18.89 (95%CI: 18.88–18.90) and VE was 98.54% (95%CI: 94.89–99.73). Consequently, P c was 112.97% (95%CI: 92.29–145.52) in outbreak 1 and 96.11% (95%CI: 93.81–98.53) in outbreak 2. Conclusion: Because of the lower VE in outbreak 1, measles virus transmission could not have been stopped even if all students received a single dose of vaccine. In outbreak 2, with higher VE, the outbreak could have been prevented by increasing the proportion of students who had been vaccinated.