The United States has reported the largest number of measles cases in the country in a single year since 1994 and since measles was eliminated in 2004, according to Morbidity and Mortality Weekly Report posted April 29 2019.1

Cases of the highly contagious acute viral illness have reached 704 as of April 26, 2019, compared with 963 cases reported in 1994. Of these reported cases, 71% were people who were not vaccinated; 11% received ≥1 measles, mumps, and rubella (MMR) vaccine; and the vaccination status of 18% was unknown. No deaths have been reported; however, 9% of patients were hospitalized and 3% had pneumonia.

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Nearly all cases, 94%, were associated with the 13 outbreaks that have been reported in 2019. The numbers of cases occurring in US residents is also high, at 98%. In 44 cases, the disease was directly imported from another country, and 77% of cases occurred in US residents. Of the 44 imported cases, 91% occurred in unvaccinated persons or persons whose status was not known.

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According to the report’s authors, outbreaks in close-knit communities accounted for 88% of all cases, and close-knit communities with low vaccine coverage are at risk for sustained outbreaks. In addition, unvaccinated US residents traveling internationally are at risk of acquiring the disease. The report recommends that, “high coverage with MMR vaccination is the most effective way to limit transmission and maintain elimination of measles in the United States,” and “health care providers should vaccinate persons without contraindications and without acceptable evidence of immunity to measles before travel to any country outside the United States.”

Of note, the CDC has updated information on the outbreak, and presently reports a total of 839 individual cases of measles in the United States.2


1. Patel M, Lee AD, Redd SB, et al. Increase in measles cases – United States, January 1-April 26, 2019. MMWR Morb Mortal Wkly Rep. 2019;68:402-404.

2. Centers for Disease Control and Prevention. Measles Cases and Outbreaks. May 13, 2019. Accessed May 16, 2019.