Paunio M, Peltola H, Valle M, Davidkin I, Virtanen M, Heinonen O P
Department of Public Health, University of Helsinki, Finland.
Am J Epidemiol. 1998 Dec 1;148(11):1103-10. doi: 10.1093/oxfordjournals.aje.a009588.
Even high levels of measles vaccination coverage have not always prevented outbreaks of measles spread by airborne transmission. It has been suggested that a large inoculum might increase vaccine failure risk. Airbome transmission might occasionally entail a large measles inoculum. The epidemiologic relevance of measles among properly vaccinated persons (i.e., those vaccinated after 15 months of age and with live attenuated virus) is increased when they become contagious. The authors studied inoculum intensities as measured by proxy variables and the contagiousness of properly vaccinated persons who contracted measles among 51 measles patients infected in one school, at home, or elsewhere, utilizing preexisting records of measles cases and 214 healthy controls from an explosive school outbreak that occurred in a rural Finnish municipality in 1989. One "super-spreader" infected 22 others in one day, including eight once-vaccinated students and one twice-vaccinated student, probably during an assembly of 144 students in a poorly ventilated hallway with no sunlight. Those infected later at home had high measles risk, even if they were revaccinees. When siblings shared a bedroom with a measles case, a 78 percent risk (seven out of nine children) was observed among vaccinees. Vaccinees had approximately 2 days' shorter incubation time than unvaccinated persons. Vaccinated and unvaccinated students were equally able to infect their siblings. Total protection against measles might not be achievable, even among revaccinees, when children are confronted with intense exposure to measles virus.
即使麻疹疫苗接种覆盖率很高，也并非总能预防通过空气传播的麻疹暴发。有人认为，大量的接种物可能会增加疫苗接种失败的风险。空气传播偶尔可能会带来大量的麻疹接种物。当接种过疫苗的人（即15个月龄后接种减毒活病毒疫苗的人）具有传染性时，麻疹在他们当中的流行病学关联性就会增加。作者利用1989年芬兰一个农村市镇发生的一起学校爆发疫情中麻疹病例的现有记录以及214名健康对照，研究了通过替代变量衡量的接种物强度以及在一所学校、家中或其他地方感染麻疹的51名麻疹患者中接种过疫苗且感染麻疹的人的传染性。一名“超级传播者”在一天内感染了另外22人，其中包括8名曾接种过一次疫苗的学生和1名接种过两次疫苗的学生，可能是在144名学生在通风不良、没有阳光的走廊集会期间。那些后来在家中感染的人即使接种过疫苗也有很高的麻疹感染风险。当兄弟姐妹与麻疹患者共用一间卧室时，在接种过疫苗的人中观察到78%的感染风险（9名儿童中有7名）。接种过疫苗的人的潜伏期比未接种疫苗的人短约2天。接种过疫苗和未接种疫苗的学生感染其兄弟姐妹的能力相当。当儿童面临强烈的麻疹病毒暴露时，即使是再次接种疫苗的人也可能无法实现对麻疹的完全防护。
