Measles transmission and vaccine effectiveness during a large outbreak on a densely populated island: Implications for vaccination policy
Measles transmission and vaccine effectiveness during a large outbreak on a densely populated island: Implications for vaccination policy
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DOI：
10.1086/498902
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发表时间：
2006-02-01
影响因子：
11.8
通讯作者：
LeBaron, CW
中科院分区：
文献类型：
--
作者：
Marin, M;Nguyen, HQ;LeBaron, CW
背景。马绍尔群岛共和国（RMI）是一个与美国自由联系的南太平洋国家。2003年，尽管一剂麻疹-腮腺炎-风疹（MMR）疫苗的报告覆盖率为80%-93%，但该地区经历了十多年来美国或其相关地区最大的麻疹暴发。在51,000人口中有135,000人接种疫苗后，疫情才结束。据报告，在暴发病例中，41%以前曾接种过疫苗。我们研究了RMI家庭的麻疹发病率，以评估疫苗的有效性和疾病传播模式。在家庭二次发病率研究中，采用麻疹暴发病例方便抽样的方法选择家庭。原发病例定义为家庭中第一个患麻疹的人。继发病例为在原发病例起疹后7-18天出现麻疹的家庭成员。疫苗有效性分析仅限于6个月至14岁的儿童，并根据书面记录验证了疫苗接种情况。72个家庭参与了这项研究。住户人数中位数为11人，每间房中位数为5.5人。继发性病例比原发性病例更有可能是婴儿（46%对13%）。1剂MMR疫苗的有效性为92%(95%可信区间[CI]， 67%-98%)， 2剂的有效性为95%（95%可信区间[CI]， 82%-98%）。麻疹疫苗效力高；因此，有效性降低并不是疫情爆发的主要原因。在人口密度高和家庭拥挤的社区，需要非常高的人口免疫力来预防麻疹暴发和保护接种疫苗年龄以下的婴儿。这可能需要出色地实施常规两剂麻疹疫苗接种战略。
Background. The Republic of the Marshall Islands (RMI) is a South Pacific nation freely associated with the United States. In 2003, the RMI experienced the largest measles outbreak within the United States or its associated areas for more than a decade, although the reported coverage of 1-dose measles-mumps-rubella (MMR) vaccine was 80%-93%. The outbreak ended only after vaccination of 135,000 persons among a population of 51,000. Of outbreak cases, 41% were reported to have been previously vaccinated. We studied measles attack rates in RMI households to assess vaccine effectiveness and patterns of disease transmission.Methods. For the household secondary attack rate study, households were selected by convenience sampling of outbreak measles cases. The primary case was defined as the first person with measles in a household. Secondary cases were household members with measles onset 7-18 days after the primary case's rash onset. Vaccine effectiveness analysis was limited to children aged 6 months to 14 years, with vaccination status verified against written records.Results. Seventy-two households were included in the study. The median household size was 11 persons, and the median number of persons per room was 5.5. Secondary cases were more likely than primary cases to be infants (46% vs. 13%;). MMR vaccine effectiveness was 92% (95% confidence interval [CI], 67%-98%) Pp. 03 for 1 dose and 95% ( 95% CI, 82%-98%) for 2 doses.Conclusions. Measles vaccine effectiveness was high; thus, diminished effectiveness was not the main cause of the outbreak. In communities with high population density and household crowding, very high population immunity is needed to prevent measles outbreaks and to protect infants below the age of vaccination. This may require excellent implementation of a routine 2-dose measles vaccination strategy.