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Continued measles importation threatens unvaccinated in US
More than 80% of the measles cases reported to the CDC between January and April occurred in people who were unvaccinated or of unknown vaccination status, recent data indicate.
“The continued risk for importation of measles into the United States and occurrence of measles cases and outbreaks in communities with high proportions of unvaccinated persons highlight the need for sustained, high vaccination coverage across the country,” Nakia S. Clemmons, MPH, and colleagues at the CDC wrote in a recent MMWR.
Between Jan. 4 and April 2, there were 159 measles cases from 18 states reported to the CDC. Patient were aged 6 weeks to 70 years, and 22 patients were hospitalized. Five patients developed pneumonia; no other complications and no deaths were reported, the researchers said.
There were four outbreaks during this period, the largest of which accounted for 70% of all measles cases this year. Most of the people involved in this year’s outbreaks have been unvaccinated (45%) or of unknown vaccination status (38%), according to the investigators.
Ninety-six percent of the measles cases were associated with importations of the disease. The researchers found that 10 cases were direct importations; six involved unvaccinated U.S. citizens returning from overseas travel, and four involved foreign visitors.
Although high two-dose vaccination coverage has eliminated measles from the U.S., importations from other countries have resulted in outbreaks that have threatened unvaccinated populations, according to the researchers.
“Most measles importations occur when U.S. citizens travel abroad and have not been appropriately vaccinated,” the researchers wrote. “Therefore, it is important to encourage timely delivery of measles vaccination for U.S. residents before overseas travel. In addition, early detection of cases and rapid public health response to outbreaks can serve to limit the spread of illness.” – by Colleen Owens
Disclosure: The researchers report no relevant financial disclosures.