MMWR reports on 6 April 2007 that measles has been eliminated from South Korea. The history of measles in South Korea provides a useful example of how immunization practices need to be flexible to achieve their goals.
Measles vaccine was first introduced into South Korea in 1965, and was included in the national immunization program in 1983 as part of the measles, mumps, and rubella vaccine. Two doses were given to children at 12-15 months and 4-6 years. Despite this approach, measles continued to occur, exemplified by an epidemic in 2000-2001 of 55,000 reported cases and seven deaths. Most of these infections occurred in children, indicating that vaccination was not sufficient and that circulation of measles virus continued.
In 2001, South Korea declared a goal of establishing measles by 2005, and developed key strategies, including requiring two doses of measles vaccine for school entry by 7 years of age; carrying out vaccination campaigns among children 8-16 years to cover those who were missed at an earlier age; and including laboratory confirmation of reported cases in the surveillance program.
These strategies have been very successful. Before the eradication plan, there were multiple measles epidemics in South Korea, with annual cases ranging from two to 32,647. As of November 2006, no cases of measles have occurred, and international authorities have concluded that measles has been eliminated from the country.
Measles virus still circulates in much of the world, and therfore immunization must be continued in South Korea if the disease is to be kept in check. If there is any relaxation of immunization – likely given that the infection is no longer a problem – the virus is likely to spread again.
WHO has declared that after polio is eradicated, they will turn their efforts to measles virus. While the outcome of measles immunization programs in South Korea will surely be used to promote the global effort, it will be much more difficult to eradicate the disease globally.