Measles Threat Still Looms; Vaccination Urged
Lower Vaccine Rates Prompting Resurgence of Measles in Some Areas
Oct. 4, 2004 -- Although the number of measles cases reported in the U.S. each year has fallen dramatically, a new report shows that the resurgence of measles in other areas of the world means measles still poses a threat at home, and children not vaccinated appropriately may be more than 60 times more likely to suffer from the potentially deadly disease.
Before routine measles vaccination became a part of the childhood immunization program in 1963, between 3 and 4 million cases were reported in the U.S. each year, resulting in several thousand deaths. That number has since fallen to less than 100 cases per year.
However, the World Health Organization estimates that about 30 million measles cases were reported worldwide in 2001 and resulted in more than 745,000 deaths in children under age 15.
"As long as measles circulates in other countries, measles will be imported into the United States," write researcher H. Cody Meissner, MD, of Tufts University School of Medicine in Boston, and colleagues.
For example, of the 116 measles cases reported in 2000, researchers say 54 of them were acquired abroad and brought into the U.S. by travelers, and 62 of the cases acquired in the U.S. were linked to these foreign-contracted cases.
In their study, appearing in the October issue of Pediatrics, researchers say progress has been made in the fight against measles but several challenges remain before the disease can be eradicated worldwide.
Next Steps in Eradication of Measles
Researchers say the first step toward global eradication of measles is for developed countries, like the U.S., to recognize that measles is a serious disease with deadly consequences.
In addition, the recent rise of measles cases in less-developed parts of the world shows that severity of the disease may not be appreciated in these countries as well. Many of these countries have a single-dose measles vaccination program that may leave a growing number of people vulnerable to the disease over time.
A second dose of the measles vaccine was added to the recommended immunization schedule in the U.S. in 1989 after research showed some children do not gain full immunity to the disease after only one dose. About 95% of children who receive a single measles vaccine after 12 months of age will become immune, but after a second dose more than 99% of children develop immunity.
Researchers say developing countries that frequently experience measles outbreaks often recommend immunization of children under 12 months of age because of the increased risk of infection. But this results in even lower rates of protection over time: About 15% of all vaccinated children remain susceptible to disease after a single vaccination at 9 months.
Another challenge to be overcome is setting the record straight after erroneous accusations about the risks associated with the measles, mumps, and rubella (MMR) vaccine.
Researchers say measles vaccination programs suffered a setback in the late 1990s after a report appeared linking the MMR vaccine, specifically the measles component, to autism. But the authors later retracted that interpretation of a causal relationship between the vaccine and autism-related disorders, and other researchers have been unable to duplicate the findings of the initial report.
The controversy surrounding the report caused measles immunization rates to fall to less than 80% in some areas of Europe, which prompted a subsequent rise in measles cases, hospitalizations, and related deaths.
Finally, researchers say measles is more severe in people with HIV and the growing AIDS epidemic means a growing number of individuals may be at risk for contracting the disease.