An outbreak of measles in a prison in Yorkshire, England, December 2012-January 2013.

Measles is a highly infectious disease with a high reproduction rate [1]. For every index case occurring in a susceptible population, 15–17 secondary cases will occur [1]. The most effective way to control measles is by active immunization of a high proportion of the population [2]. MMR vaccine was introduced in the UK in October 1988 and achieved coverage levels in excess of 90% [3]. Prior to this measles vaccination coverage was low and transmission was largely unaffected. According to seroprevalence studies <1% of individuals born before 1970 and <10% born between 1970 and 1989 are antibody negative to measles [4, 5]; however, despite measles vaccination programmes residual susceptibility is present in young adults [6]. We describe an outbreak of measles occurring in a prison in Yorkshire that began in December 2012.