In 2000, the U.S. Centers for Disease Control and Prevention (CDC) declared measles eliminated from the United States, meaning continuous disease transmission had been interrupted. However, measles continues to be imported through international travel, and outbreaks can occur when the virus is introduced into under-vaccinated communities. Recent years have seen substantial increases in measles activity nationwide, highlighting the importance of vaccination and infection prevention measures in healthcare settings.
What is measles and how is it transmitted?
Measles is a highly contagious acute viral respiratory illness that is transmitted by direct contact with infectious droplets that are be released into the air when an infected person breathes, coughs or sneezes. It can remain infectious in the air for as long as two hours after the infected person has left the area. As a result, measles is one of the most contagious of all infectious diseases. Infected people are considered contagious from four days before to four days after the rash appears.
How prevalent is it?
Measles activity in the United States has increased significantly in recent years. According to the CDC, as of October 1, 2026, 3,887 confirmed measles cases had been reported in 47 U.S. jurisdictions, with 95% of cases associated with outbreaks. For comparison, 2,289 cases were reported during all of 2025 and 285 cases during 2024. Most outbreaks continue to occur in communities with lower vaccination coverage and may be initiated by international travel-related importations.
Because measles epidemiology changes rapidly, readers should consult the CDC's Measles Cases and Outbreaks webpage for current case counts and outbreak information.
How effective is the measles vaccine?
CDC recommends two doses of measles-containing vaccine. The first MMR dose is routinely administered at age 12-15 months and the second at age 4-6 years. Two doses of measles vaccine are approximately 97% effective at preventing measles, while one dose is approximately 93% effective. Most vaccinated individuals remain protected for life.
Who should be vaccinated?
The CDC has age-specific recommendations. Children should receive the first MMR immunization between the ages of 12-15 months and a second dose between ages four and six or at least 28 days after the first dose. Students at post-high school educational institutions who cannot provide proof of immunity should have two doses of the MMR vaccine spaced at least 28 days apart. The agency recommends that adults born during or after 1957 who do not have evidence of immunity against measles should get at least one dose of MMR vaccine. The agency also has specific recommendations for people of all ages who travel internationally.
How can I prevent transmission in my practice? What should I do if a member of my staff is exposed to measles?
Continuing to follow standard universal precautions remains the best method of reducing the chance of transmitting measles to staff and other patients. The CDC’s Advisory Committee on Immunization Practices (ACIP) recommends that people working in healthcare settings have documented evidence of immunity against measles. The dental practices’ standard human resources/infection control protocols should include confirmation that staff records and staff immunizations are up to date. Staff exposed to measles who cannot readily show that they have evidence of immunity against measles should be offered post-exposure prophylaxis (PEP) or be excluded from the practice setting. Measles PEP may involve being given the MMR vaccine, which may provide some protection or modify the clinical course of disease if given within 72 hours of initial measles exposure, or immunoglobulin (IG), if given within six days of exposure.
Dental employers should ensure that all dental healthcare personnel have documented evidence of immunity to measles consistent with CDC recommendations. Prevention of transmission in dental settings includes verification of immunity status, rapid identification of suspected measles cases, prompt patient isolation, use of airborne precautions, and appropriate management of exposed personnel.
How can my staff and I tell if a patient has it?
Many of the symptoms of measles become apparent within one to two weeks of infection and can include high fever, cough, runny nose, conjunctivitis, rash, and, in some cases, tiny white spots inside the mouth. The measles rash typically spreads from the head to the trunk to the lower extremities.
What should we do if a patient has it? Or if we suspect the patient has it?
Patients with suspected measles should be identified before arrival whenever possible. Dental offices should consider screening patients reporting fever with rash, recent international travel, or known exposure to measles. Suspected cases should be masked, separated from other patients, and evaluated using airborne infection-control precautions. Dental healthcare personnel entering the treatment area should use a fit-tested N95 respirator or equivalent respiratory protection. Suspected cases should be reported promptly to local or state public health authorities.
Resources
From the ADA:
- Hand Hygiene
- From the Journal of the American Dental Association: Managing measles in dental practice: A forgotten foe makes a comeback [PDF]. July 2015 Volume 146, Issue 7, Pages 558–560.
From the CDC:
- Measles (Rubeola) | CDC Comprehensive information for Health care professionals, Public Health dept and general public.
- Healthcare Personnel Safety Component (HPS) | NHSN | CDC
- Infection Control CDC
- Chapter 7: Measles | Manual for the Surveillance of Vaccine-Preventable Diseases | CDC