A look at how measles comes into the United States highlights needs for both more vigilant vaccination efforts, and support for global efforts to eliminate the disease, according to a report in an upcoming Journal of Infectious Diseases.
While measles was declared eliminated in the United States in 2000, over the years since then 553 cases have been imported into the country from regions where the virus remains endemic. Fueling local transmission, they have made up more than a quarter of the 2,098 cases confirmed here between 2000 and 2016, the authors of the report write. While global measles elimination efforts have seen case rates drop by 87 percent since 2000, the authors note, the virus remains a public health threat over much of the world. Primarily airborne, measles spreads easily, with a “secondary attack” rate of about 90 percent among those in proximity to an infected person.
The majority of those imported cases, 62 percent, were brought home by U.S. residents traveling abroad. About 62 percent of the cases, also, overall, were brought in from the Western Pacific and European World Health Organization regions the authors note. Of all of the imported cases, 87 percent were confirmed in patients who either had not been vaccinated against measles at all, or whose vaccination status was unknown.
The U.S. Centers for Disease Control and Prevention recommend that all U.S. residents be vaccinated with two doses of the measles, mumps and rubella — MMR — vaccine, the first at 12-to-15 months of age, and the second at 4-to-6 years. Because of increased risks of exposure overseas, however, the authors write, infants who are 6 months to a year old should receive one dose before leaving the country, and anyone older than a year should have both doses, separated by at least four weeks.
In addition to underscoring the need to follow that guideline, the authors write, the findings highlight the need for strong support for global measles elimination efforts.
An advance copy of the report, International Importations of Measles Virus into the United States during the Post-Elimination Era, was published online Monday.