Measles in the U.S. - MMR vaccination information for travelers and others

The current increase in measles cases in the United States is mostly due to importations into under-vaccinated communities by U.S. residents returning from international travel https://www.cdc.gov/mmwr/volumes/68/wr/mm6817e1.htm). The CDC measles team has developed the following summary for measles, mumps, rubella (MMR) vaccination of international travelers and persons living in or traveling domestically to areas with ongoing measles outbreaks and community-wide transmission. 

INTERNATIONAL TRAVEL

The MMR vaccination recommendations for international travel have not changed.  https://www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm

Before departure from the United States, travelers aged ≥6 months who do not otherwise have acceptable presumptive evidence of measles immunity* should be vaccinated with MMR vaccine (at least two weeks prior to travel, if possible).

  • Infants aged 6 through 11 months should receive one dose of MMR vaccine. Infants who receive one dose of MMR vaccine before their first birthday should receive two more doses according to the routinely recommended schedule (one dose at 12 through 15 months of age and another dose at 4 through 6 years of age or at least 28 days later).
  • Children aged ≥12 months, teens, and adults born during or after 1957 who do not have other evidence of measles immunity* should receive two doses of MMR vaccine, with each dose separated by at least 28 days.

Acceptable Presumptive Evidence of Measles Immunity for International Travelers

  • Birth before 1957 or
  • Laboratory confirmation of disease or
  • Laboratory evidence of immunity or
  • Written documentation of receipt of MMR vaccine
    • 1 dose for infants aged 6-11 months
    • 2 doses for persons aged ≥ 12 months

DOMESTIC MEASLES OUTBREAKS

The MMR vaccination recommendations for persons residing in or visiting domestic measles outbreak areas within the U.S. have not changed. Providers should ensure that people who live in and are traveling to areas in the U.S. where there is ongoing, community-wide transmission of measles are up to date on MMR vaccine

https://www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm

https://www.cdc.gov/vaccines/pubs/surv-manual/chpt07-measles.html

  • If the outbreak has demonstrated community-wide transmission and affects preschool-aged children, consider a second dose of MMR for children aged 1 to 4 years who reside in or are visiting the outbreak area. If the outbreak affects adults, consider a second dose for adults who have previously received one dose.
  • For outbreaks in close-knit communities that have demonstrated ongoing, community-wide transmission, providers may consider an early dose of MMR vaccine for infants aged 6 through 11 months who are residing in or visiting the outbreak area if the outbreak affects infants aged <12 months, and there is ongoing risk for exposure to the infant.


Providers should follow recommendations issued by the local health department of the affected community regarding MMR vaccination of residents of or visitors to the area.
They should weigh the benefit of protection against measles during an outbreak against the risk of decreased immune responses in infants vaccinated with MMR before 12 months of age. For example, if no vaccination recommendation was made by the local health department for infants aged 6 through 11 months living in the outbreak community, then vaccination of infant travelers visiting the outbreak area is also not recommended. 

Additional information regarding vaccination of infants aged 6 through 11 months traveling domestically to areas with measles outbreaks:

  • Infants younger than 12 months of age are at greatest risk of severe infection. Vaccination of infants aged 6-11 months minimizes the risk of morbidity and mortality that would occur by delaying vaccination during measles outbreaks.
  • Seroconversion rates (i.e., the percentage of children who develop detectable levels of antibody) and the titers of protective neutralizing antibodies are lower in children vaccinated at younger than 12 months of age than in children vaccinated later. Therefore, the recommendation is to revaccinate these infants according to the routine 2-dose schedule. Although revaccination is very effective, titers of neutralizing antibodies may remain lower than in children who received their first dose at ≥12 months of age. This could result in an increase in susceptibility to measles over time.

References regarding immune responses in infants vaccinated less than 12 months of age: 

  1. Kumar ML, Johnson CE, Chui LW, et al. Immune response to measles vaccine in 6-month-old infants of measles seronegative mothers. Vaccine 1998;16:2047–51.
  2. Gans HA, Arvin AM, Galinus J, et al. Deficiency of the humoral immune response to measles vaccine in infants immunized at age 6 months. JAMA 1998;280:527–32.
  3. Krugman S.: Present status of measles and rubella immunization in the United States: a medical progress report. J Pediatr 1971; 78:1-16.
  4. Gans HA, Yasukawa LL, Alderson A, et al. Humoral and cell-mediated immune responses to an early 2-dose measles vaccination regimen in the United States. J Infect Dis 2004;190:83–90.
  5. Nkowane B.M., Bart S.W., Orenstein W.A., et al: Measles outbreak in a vaccinated school population: epidemiology, chains of transmission and the role of vaccine failures. Am J Public Health 1987; 77:434-438.
  6. Davis R.M., Whitman E.D., Orenstein W.A., et al: A persistent outbreak of measles despite appropriate prevention and control measures. Am J Epidemiol 1987; 126:438-449.
  7. Shasby D.M., Shope T.C., Downs H., et al: Epidemic measles in a highly vaccinated population. N Engl J Med 1977; 296:585-589.
  8. Hutchins S.S., Dezayas A., Le Blond K., et al: Evaluation of an early two-dose measles vaccination schedule. Am J Epidemiol 2001; 154:1064-1071.
  9. Brinkman I.D., de Wit J., Smits G. P., et al: Early measles vaccination during an outbreak in the Netherlands; Short –term and long-term decreases in antibody responses among children vaccinated before 12 months of age.  J. Infect Dis 2019

Please direct any questions to: ncirddvdmmrhp@cdc.gov