Measles is Dangerous in Adults: Who and How to Assess for the MMR Booster
The 2025 measles outbreak is predominantly affecting children, but measles is highly contagious and adults remain at risk, especially if they have not received the MMR vaccination.
The current measles outbreak is affecting all ages, but hospitalization rates are higher among adults and infants, underscoring the importance of vaccination.
People who are not vaccinated against measles are at greatest risk of severe infection - 1 in 5 unvaccinated people in the us will require hospitalization due to measles; in 2024, the rate was even higher with ~40% of people with measles hospitalized.
The known complications of measles across age groups include pneumonia, encephalitis, and subacute sclerosing panencephalitis.
The long-term health risks following measles include long-term immune system suppression, increased susceptibility to bacterial and viral diseases for months to years after infection, mortality (rates can reach 1-3 per 1,000 cases in outbreaks), and increased risk during pregnancy.
Who is eligible for an MMR vaccination or booster? Adults born after 1957 who lack documented immunity; those who received only 1 MMR dose instead of the recommended 2; healthcare workers, college students, military personnel; international travelers visiting regions where measles is still endemic; and, individuals in outbreak-affected areas or high-risk communities.
Does this adult need an MMR booster? To determine, review vaccination records, check serologic immunity and give 1 MMR dose immediately if immunity is negative, consider risk factors, and when in doubt, give the vaccine.
For any health care professional who suspects a case of measles, notify the appropriate health department/s to ensure rapid testing and investigation. Pursue laboratory confirmation with any patient with suspected measles.
