Dec. 9 (UPI) -- Less than half of all American children traveling internationally are vaccinated against measles prior to departure, even as many countries across the globe are grappling with ongoing outbreaks of the disease, a new study has found.
In an analysis published Monday in the journal JAMA Pediatrics, researchers reveal that just 41.3 percent of all children 18 years of age and younger received the MMR shot during pre-travel consultations.
The number is somewhat surprising, they said, given that there have been nearly 1,300 cases of measles in the United States so far this year -- with many of them linked to international travel.
"Most people who have been infected with measles during international travel were not vaccinated with MMR prior to departure," study co-author Emily Parker Hyle, an associate professor in the department of infectious diseases at Harvard Medical School, told UPI. "Our study highlights that... almost 60 percent of children who were eligible for vaccination did not receive it at the pre-travel visit due to providers not offering vaccination and guardians refusing it."
Last week, the World Health Organization confirmed that there were nearly 10 million cases of measles globally in 2018.
Currently, the U.S. Centers for Disease Control and Prevention recommends that everyone six months of age and older traveling internationally get vaccinated against measles.
Prior to departure, the agency says, infants between six months and 11 months of age should receive one dose of the MMR vaccine, while children 12 months of age and older should receive two doses of the shot, separated by at least 28 days.
To assess compliance with this guidance, Hyle and her colleagues reviewed the case files of pediatric travelers age six months to 18 years who attended pre-travel health consultations at 29 locations associated with GlobalTravEpiNet, a CDC-supported consortium of facilities that focus on travel medicine services. In all, researchers reviewed nearly 15,000 pre-travel consultations over a 10-year period, of which 2,864 involved travelers eligible to receive the MMR vaccine.
Of the 365 infants in this group, just 204, or 56 percent, received the shot, while only 939 of 2,161, or 43 percent, of preschool aged travelers were given the vaccine. Finally, less than 12 percent of 338 school-aged travelers included in the analysis were administered the two-dose vaccine prior to departure.
The most common reasons for non-vaccination, according to the authors, were clinician decision, in approximately 37 percent of cases, and parent or guardian refusal, in just over 36 percent of cases. Hyle and her colleagues note that although children make up only 10 percent of all foreign travelers in U.S., they account for nearly half of all "imported cases" of measles across the country.
"MMR is a safe and effective vaccine to reduce the risk of infection with measles," Hyle said. "There is enough circulating measles globally and it is so contagious that the CDC doesn't recommend a different vaccination strategy for travelers going to a country with a current outbreak versus a country without a current outbreak."
"Providers should consider MMR vaccination for eligible children who will be traveling internationally, including destinations such as Europe," Hyle said, adding that "parents and guardians should ask their children's pediatricians about MMR vaccination prior to international travel, especially for children ages six months to six years of age."