Incremental effectiveness of 2 doses of measles-containing vaccine compared with 1 dose among high school students during an outbreak.
A measles outbreak occurred among a highly vaccinated population in Alaska during 1998, providing an opportunity to determine the incremental efficacy of >or=2 doses of measles-containing vaccine (MCV) compared with 1 dose. Of 33 confirmed case patients identified, 31 had been vaccinated with 1 dose of MCV, 1 had received 2 doses, and vaccination status was unknown in 1 case. Seventy percent of cases were school-associated; 58% of cases occurred in 2 high schools. Of 3679 students attending the 2 schools, 50.4% and 45.5% had received >or=2 doses of MCV before measles introduction at the schools. The relative risk of developing measles among persons vaccinated with >or=2 doses of MCV compared with 1 dose was 0.06 (95% confidence interval, 0.01-0.44; P<.001), yielding an estimated incremental vaccine efficacy of 94.1% (95% confidence interval, 55.9%-99.2%; P<.001). Rapid implementation of a mandatory second-dose MCV requirement probably limited the extent of this outbreak.
Lynn
Tracey V
TV
Alaska Division of Public Health, Anchorage, Alaska; Epidemic Intelligence Service, Epidemiology Program Office, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. tracey_lynn@health.state.ak.us.
Beller
Michael
M
Funk
Elizabeth A
EA
Middaugh
John P
JP
Ritter
Donald
D
Rota
Paul A
PA
Bellini
William J
WJ
Torok
Thomas J
TJ
D000293:Adolescent; D000328:Adult; D000413:Alaska / Q000453:epidemiology; D002675:Child, Preschool; D015331:Cohort Studies; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007117:Immunization, Secondary; D008297:Male; D008457:Measles / Q000453:epidemiology / Q000517:prevention & control*; D022542:Measles-Mumps-Rubella Vaccine / Q000008:administration & dosage* / Q000627:therapeutic use*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014611:Vaccination; D017778:Vaccines, Combined
D022542:Measles-Mumps-Rubella Vaccine; D017778:Vaccines, Combined