Adults who don’t know they need or refuse measles vaccinations before international travel introduce more than half of new U.S. measles cases.
As physicians grapple with vaccine refusal and vaccine hesitation, one way to protect against the spread of vaccine-preventable disease is to limit its entry to the United States. In today’s global culture, a new study has found that more than half the measles cases imported to the U.S. are from adult travelers who were not immune to the disease prior to traveling abroad.
The report, published in the Annals of Internal Medicine, found that many adults traveling internationally aren’t receiving the recommended vaccination against measles, mumps and rubella (MMR) prior to travel. The American Council on Immunization Practices (ACIP) recommends that all U.S. international travelers be immune to measles before departure in order to limit the importation of the disease into the U.S. Immunity is achieved by receiving two lifetime doses of the MMR vaccine with additional markers of immunity including a positive measles serology or physician documented history of measles illness, according to the report.
Emily P. Hyle, MD, MSc, an infectious disease specialist at Massachusetts General Hospital and lead author of the report, told Medical Economics the study reveals that 16% of the 40,000 adult travelers studied between 2009 and 2014 were eligible for MMR vaccination prior to international travel, but 53% of them were not vaccinated at a pre-travel medical visit and 48% refused a physician’s recommendation for the vaccine. Another 28% of travelers were not vaccinated based on provider decision, and 24% because of health system barriers, according to the report.
“We hope that our study will raise awareness of the ACIP recommendation that all U.S. residents be immune to measles prior to international travel,” Hyle said. “Providers who see patients prior to travel should be asking about past MMR vaccinations and recommending MMR vaccination to non-immune travelers who are eligible for the MMR vaccine.”
Reminders of recent illness
Endemic measles was eliminated in the U.S. in 2000, but periodic outbreaks persist due to importation of the disease, according to the study. Most of these cases enter the U.S. through returning U.S. travelers who were not sufficiently vaccinated prior to travel. Once imported, measles can spread quickly and easily, according to the report, with 90% of unvaccinated individuals contracting the disease after exposure to an infected person. The report cites recent outbreaks at Disneyland in 2015 and in Ohio in 2014, in which one or two cases quickly grew to the hundreds.
In investigating why patients and physicians opted against the MMR vaccine before travel, the study found that 74% of patients were not concerned about illness. When physicians did not offer the vaccine, 94% of the time was because the provider thought the vaccine was not indicated, and 6% were because the physician thought there was insufficient time before travel to administer the vaccine. When health system barriers played a role, 99% of the time was because patients were referred to another provider for vaccination and patients might not follow through with the referral.
The study highlights the need for physicians to be aware of the ACIP recommendation and conduct pre-travel assessments with their patients. Efforts should be made to educate patients about the need for vaccination and ensure that barriers to proper immunization are removed, according to the report.