Reference no: EM132852290

Before this outbreak, the proportion of children vaccinated against measles on the Arkansas side was substantially higher than the proportion vaccinated on the Texas side. The Texas side had never had a community or school vaccination campaign for measles. In contrast, the Arkansas side had held mass community programs against measles for school and pre-school children in 1968 and 1969.

Based on health department and physician records, investigators estimated that over 99% of children aged 1-9 years in Miller County, Arkansas had received measles vaccine prior to the outbreak. The overall vaccination level in Bowie County, Texas, was estimated to be 57%.

In this outbreak, 27 of the measles cases in Bowie County and all 25 of the measles cases in Miller County gave a history of prior vaccination with live attenuated measles-virus vaccine. Parental history of vaccination was corroborated for all the cases by clinic or physician records. Local health authorities in both counties were very concerned that children who had previously received measles vaccine got the disease.

Calculate attack rates among the vaccinated populations in both counties and comment on your findings.