Though most US babies and preschool-age children are eligible to receive the measles, mumps, and rubella (MMR) vaccine before traveling abroad, nearly 60% weren't vaccinated before departing, revealing missed opportunities by doctors, a research team based at Massachusetts General Hospital (MGH) reported yesterday.
Since measles was eliminated in the United States in 2000, outbreaks have been linked to people who contracted the virus in other countries, half of them in US residents returning home.
The United States has reported 1,276 cases so far this year, the most since 1992, with the majority of illnesses linked to a few large outbreaks triggered by international travelers. Some of the outbreaks lasted several months, which threatened the nation's measles elimination status.
Though children make up only 10% of US international travelers, they account for nearly half of imported measles cases. Recognizing the risk of infection that young unvaccinated travelers face and their outsized threat of spreading the disease once they arrive home, special MMR recommendations for young international travelers have been in place since 1989.
Researchers uncover vaccination gaps
To see how well doctors follow recommendations for young international travelers, researchers looked at the records of more than 14,000 pediatric travelers who were seen for pretravel health visits at Global TravEpiNet sites, a consortium supported by the Centers for Disease Control and Prevention, from 2009 to 2018. They published their findings in JAMA Pediatrics.
Typically, children receive two MMR doses, the first between 12 and 15 months and the second between 4 and 6 years. Due to the risk of international measles exposure, babies ages 6 to 12 months old who will travel are recommended to get vaccinated earlier and receive one dose before departure, with preschoolers advised to have received both lifetime doses before they leave.
Of the children seen at the clinics, 92% of infants and 60% of preschool-age kids were eligible for MMR vaccination, but 44% of babies and 57% of preschoolers weren't vaccinated, usually, because the clinicians didn't recognize that the children were eligible. In many instances, the children's' guardians also didn't want them vaccinated.
The study found that only 3% of school-aged travelers were eligible for vaccination, which researchers said points to overall high vaccine coverage. However, that group wasn't typically vaccinated due to guardian refusal, even though there were several measles outbreaks and robust media coverage of them.
Regina LaRocque, MD, PhD, senior author of the study who is with the MGH Division of Infectious Diseases, said in an MGH press release, "This underscores the knowledge gaps that exist about MMR vaccination, even among clinicians with expertise in travel medicine."
A pre-travel role for doctors
The group wrote that more study is needed to determine why clinicians didn't identify MMR-eligible kids or did not administer the vaccine, which they said would help educate providers and improve implementation of vaccination recommendations for young travelers.
Researchers concluded that clinicians have a role to play in discussing the risks of contracting measles abroad and how serious the disease can be. "Clinicians are trusted sources of information about vaccinations and should take advantage of every opportunity to address vaccine effectiveness, even in the context of previous vaccine refusal," they wrote.
Dec 9 JAMA Pediatr abstract
Dec 9 MGH press release