Impact of a measles outbreak response immunization campaign: Maroua, Cameroon, 2009.

A large measles outbreak occurred in Maroua, Cameroon during October 2008-April 2009; a nine-day outbreak response immunization (ORI) campaign was initiated 15 weeks after the start of the outbreak during high transmission season. To assess the impact of ORI, we described changes to case counts and characteristics before and after ORI, and the reporting efficiency of measles cases to the surveillance system. A sharp decrease in cases occurred from 555 cases during the period before ORI to 162 cases during the period after ORI; reporting efficiency was 79.