: In 2009 and 2010 a series of measles outbreaks, involving different age groups, occurred
in rural areas of the Chabahar district in southeast Iran. These outbreaks raised questions regarding the
effectiveness of immunization programs in these areas. To determine the most important factors leading
to these outbreaks, and to determine the effectiveness of the measles vaccination program, the present
study analyzed surveillance data and performed a case-control study. The total number of reported
cases during the study period was 126. The estimated vaccine effectiveness, based on the adjusted odds
ratio of the case-control study, was 74.2z (95z CI, 10.2–92.6). On two occasions, both primary and
secondary cases of the outbreaks were vaccinated school children. In total, 42z of all cases were aged
above 7 years, and 6.3z were above 20 years. With regard to the important role of schools as the foci of
contact between uninfected and infected children, supplementary immunization of children before starting
in school could be effective in preventing measles outbreaks. In addition, implementation of supplementary
immunization every 5–10 years in older age groups might be effective in preventing future
outbreaks.