virology blog

About viruses and viral disease

Events

Eradication of Measles in South Korea

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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.

Marshall Horwitz

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I note the recent passing of Marshall Horwitz on 31 May 2005. Dr. Horwitz was an internationally recognized virologist who made important contributions to our understanding of adenoviruses, causative agents of respiratory, enteric, and opthalmologic infections. In the course of his career he studied many aspects of the biology of adenovirus, including how the DNA genome replicates, how the virus enters cells, and the immune response to infection. Most recently his work focused on how adenovirus modulates the antiviral response of the host, a very important topic in virology.

The official Einstein College of Medicine announcement can be found here.

Maurice Hilleman

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I note the recent passing of Maurice Hilleman on 11 April 2005. Dr. Hilleman was a giant in the field of vaccines. Working at Merck & Co., he developed 8 of the 14 commonly used vaccines: measles, mumps, hepatitis A, hepatitis B, chickenpox, meningitis, pneumonia, and Haemophilus. Among his other achievements, he found that SV40 was a contaminant of early poliovirus vaccines.

The official Merck announcement can be found here.

Jonas Salk’s Poliovaccine

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Yesterday was the 50th anniversary of the licensing of the first vaccine against poliomyelitis, the inactivated poliovaccine (IPV) developed by Jonas Salk.

On 12 April 1955, the results of the clinical trial of IPV were announced. The trial, supported by the National Foundation for Infantile Paralysis (NFIP) and organized by Thomas Francis of the University of Michigan, involved 1.8 million children. Francis and Salk announced that the vaccine was safe and effective; later that day five pharmaceutical companies were granted licenses to produce the vaccine.

From 1955 to 1962, 400 million doses of IPV were distributed in the U.S. The incidence of poliomyelitis was reduced from about 20,000 cases per year to 2,500 cases per year. In 1961, Albert Sabin’s oral poliovaccine (OPV) was selected to replace IPV in the U.S. The use of OPV lead to the eradication of poliomyelitis caused by wild type virus in the U.S. by 1979. In 2000, OPV was replaced by IPV in the U.S.

The IPV clinical trial was a huge event in medical history, and the success of the vaccine was a relief to millions of people at risk for infection with poliovirus. While Salk was declared a hero, the important contributions of Thomas Francis in conducting the clinical trial must not be forgotten.