Vitek C R, Aduddell M, Brinton M J, Hoffman R E, Redd S C
Epidemiology and Surveillance Division, National Immunization Program, US Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Pediatr Infect Dis J. 1999 Jul;18(7):620-3. doi: 10.1097/00006454-199907000-00010.
In 1989 a second dose of measles vaccine was recommended for US children to prevent school outbreaks of measles. Coverage of school age children with a second dose remains incomplete, and data on the effectiveness of this recommendation are limited. We investigated a measles outbreak in Mesa County, CO, in December, 1994, and evaluated the efficacy of preoutbreak immunizations at an elementary school (School A) where many students had received two doses.
All reported suspected cases of measles were investigated; cases that met a clinical case definition were tested by a measles IgM antibody assay. A confirmed case required laboratory confirmation or had to meet the clinical case definition and be epidemiologically linked to a confirmed case. Vaccination records of students at School A were reviewed. The effectiveness of one and two doses of measles vaccine was estimated using logistic regression.
Sixty-two confirmed cases were reported, including 17 at School A. At School A the attack rate in unvaccinated children (7 of 16, 44%) was higher than in those with 1 dose (10 of 320, 3%) or 2 doses (0 of 289, 0%). Estimated vaccine effectiveness was 92% for 1 dose and 100% for 2 doses. Two doses were better than one dose in decreasing the likelihood of acquiring measles (P = 0.003).
The lower attack rate among two dose recipients provides evidence that a two dose strategy can help prevent measles in schools. Administering the second dose at elementary school entry can help prevent the persistence of susceptible cohorts of children and is likely to be important in sustaining elimination of indigenous transmission of measles in the United States.
1989年，美国建议为儿童接种第二剂麻疹疫苗，以预防学校内的麻疹暴发。学龄儿童第二剂疫苗的接种率仍不完整，关于这一建议有效性的数据也很有限。我们调查了1994年12月科罗拉多州梅萨县的一次麻疹暴发，并评估了一所小学（A校）在暴发前进行免疫接种的效果，该校许多学生已接种两剂疫苗。
对所有报告的疑似麻疹病例进行调查；符合临床病例定义的病例通过麻疹IgM抗体检测进行检测。确诊病例需要实验室确认，或必须符合临床病例定义并在流行病学上与确诊病例相关联。查阅了A校学生的疫苗接种记录。使用逻辑回归估计一剂和两剂麻疹疫苗的有效性。
报告了62例确诊病例，其中A校有17例。在A校，未接种疫苗儿童的发病率（16人中7例，44%）高于接种1剂疫苗的儿童（320人中10例，3%）或接种2剂疫苗的儿童（289人中0例，0%）。估计一剂疫苗的有效性为92%，两剂疫苗的有效性为100%。两剂疫苗在降低感染麻疹可能性方面优于一剂疫苗（P = 0.003）。
两剂疫苗接种者较低的发病率证明，两剂疫苗接种策略有助于预防学校内的麻疹。在小学入学时接种第二剂疫苗有助于防止易感儿童群体的持续存在，这对于在美国持续消除麻疹的本土传播可能很重要。
