Measles outbreak in Juneau, Alaska, 1996: Implications for future outbreakcontrol strategies

Objective. To determine the most effective outbreak control strategy for sc hool-based measles outbreaks as the proportion of children with two doses o f measles-containing vaccine (MCV) increases. Setting. A school-based measles outbreak during 1996 involving 63 cases in Juneau, Alaska (population 29 288), where systematic revaccination with MCV was not implemented. Design. A retrospective evaluation using chain-of-transmission data of thre e possible outbreak control strategies: no school revaccination, targeted s chool revaccination (affected schools only), and community-wide school reva ccination (all schools). Two-dose MCV coverage among students was estimated from school vaccination records and a survey issued to parents. Primary Outcome Measures. Potentially preventable cases of measles and dose s of MCV administered per case prevented. Results. Two-dose MCV coverage among Juneau students was estimated to be 44 % and 53% immediately before and after the outbreak, respectively. Of all t he measles cases, an estimated 24 to 28 and 2.7 to 31 were potentially prev entable by the targeted and communitywide school revaccination strategies, respectively. Either strategy might have optimally decreased the outbreak d uration by 1 month, sparing one of seven affected schools and 10 of 12 unva ccinated children who had measles. Approximately 133 to 155 and 139 to 160 doses of MCV per case prevented would have been required for targeted and c ommunity-wide school revaccination, respectively. Conclusions. Either targeted or community wide school revaccination would h ave been effective control strategies for this outbreak. Targeted school re vaccination is probably the intervention of choice for school-based measles outbreaks in larger communities with higher two-dose MCV coverage. As two- dose MCV coverage continues to increase in the United States, public health control measures to respond to outbreaks need to be reevaluated.