Mumps Outbreak in a Recently Vaccinated Population - Kosrae, Federated States of Micronesia, August–December, 2017

On Aug 6, 2017, the Kosrae Department of Health Services (KDHS) in the Federated States of Micronesia identified a confirmed case of mumps in a Kosrae resident who had 2 documented doses of measles-mumps-rubella (MMR) vaccine. The patient aged 18 years had recently traveled to Seattle, Washington, which was experiencing a mumps outbreak among members of its Pacific Islander population. Other Pacific Islands were concurrently experiencing large mumps outbreaks, in some places exceeding 500 cases, raising concern about the possibility of a similar outbreak in Kosrae. KDHS declared the end of the outbreak on Dec 15, 2017. Unlike mumps in other Pacific Island communities, this outbreak remained small. The analysis suggests that the interval since last MMR dose contributed to mumps acquisition, and the 2014 campaign dose of MMR might have prevented further spread.