By Carol A. Kemper, MD, FACP

Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Kemper reports no financial relationships relevant to this field of study.

SOURCE: Hyle EP, Rao SR, Jentes ES, et al. Missed opportunities for measles, mumps, rubella vaccination among departing U.S. adult travelers receiving pre-travel health consultations. Ann Intern Med 2017;167:77-84.

Outbreaks of measles continue to occur in the United States, mostly because of imported cases. More than half of these occur as the result of inadequately vaccinated returning U.S. travelers who acquire measles infection abroad. And the problem is not limited to those returning to the United States. On any given day, only 86% of persons at Disneyland have received MMR vaccine, far below the threshold for herd protection in the event of an outbreak. The recent measles outbreak at Disneyland in 2014-2015 resulted in 125 measles infections, 110 of which occurred in Californians. Nearly half (45%) were unvaccinated, most for non-medical exemption.

Investigators surveyed 54,100 departing U.S. adult travelers for measles immunity and eligibility for MMR between 2009 and 2014. Travelers were evaluated at one of 24 sites with Global TravEpiNet, which is a consortium of travel clinics, 14 of which are based at academic centers and 10 at primary care practices, public health facilities, or pharmacies. Travelers born before 1957 were considered immune and excluded from analysis (n = 13,290 adults). Of those remaining, the median age was 33 years (range, 26-44 years). The most common travel destinations included Africa (35%) or Central or South America (28%), and the median duration of planned travel was two weeks. Most travelers born after 1957 were deemed to be measles-immune (84%), based on a history of receiving two doses of measles vaccine (73%), serologic testing (10%), and/or a history of measles infection (3%), and/or provider judgment (18%). Only a small number (0.3%) were ineligible for vaccination for medical reasons. The remaining 16% were eligible for MMR. MMR was offered to anyone eligible for vaccination; 53% did not receive MMR during their visit. The most common reason was patient refusal (48%). In 28% of cases, vaccination was not provided based on provider decision 94% of the time because the provider thought the vaccine was unnecessary and 6% of the time because of insufficient time before travel. “Health system barriers” were listed as the reason for non-vaccination in 24% of cases, largely due to referral to an outside provider. For the 1,698 travelers who refused the vaccine, three-fourths indicated they were “not concerned about illness,” 20% were concerned about vaccine safety, and a small percentage (6%) were concerned about vaccine cost.

Many travelers remain unaware of the risks of illness abroad and the need for good travel advice and immunization. Too often, I’ve argued with patients who weigh the imagined risk of illness against the inconvenience and expense of vaccination, and lost the argument. This survey also demonstrates that at least one-fourth of missed MMR vaccine was the result of provider decision, suggesting travel clinic providers would benefit from additional education about the benefits and need for MMR vaccination in eligible travelers.