Approach to verify the status of measles, rubella, and congenital rubella syndrome elimination in Costa Rica.

Costa Rica introduced the measles-mumps-rubella (MMR) vaccine in 1986. The Ministry of Health adopted the goal of eliminating endemic measles in 1991 by achieving and maintaining high vaccine coverage through routine delivery, mass campaigns and outreach activities, and the strengthening of expanded program on immunization (EPI) surveillance. Measles and rubella immunization strategies shifted susceptibility to older age groups, leading to the introduction of MMR2 in 1992, administered at age 7 years. In 2000, the goal of accelerated rubella control and congenital rubella syndrome prevention was established, and a nationwide vaccination campaign targeting men and women aged 15-39 was implemented to immunize the population of reproductive age. The last endemic case of measles was confirmed in 1999, and at the end of 2001 Costa Rica reported the last endemic cases of rubella and congenital rubella syndrome. Imported cases of measles and rubella were detected in 2003 and 2005, with no secondary cases detected. In 2008, Costa Rica established a National Committee of Experts, supported by technical teams, to collect the evidence required to verify the interruption of endemic transmission of the measles and rubella viruses. The evidence includes information on trends and epidemiologic analysis, molecular epidemiology, population immunity, the quality of surveillance, and the sustainability of the EPI program.