There's a Measles Alert in My Area. Now What?

Driven by declining MMR vaccination rates, increased international travel, and pockets of low herd immunity, measles cases have surged significantly in the U.S. In 2025, the nation saw the highest levels of measles since 1991, with 2,280 confirmed cases. As of February 19, 2026, there have already been 982 confirmed cases this year. 

Many of these cases are currently localized in states with large outbreaks—Arizona, Utah, and South Carolina—but because measles is highly contagious (a single infectious person can potentially infect 18 healthy others), even people living in non-affected areas are at risk.  

To quickly notify the public of potential exposure sites and prevent further spread, health authorities issue measles exposure alerts—often delivered via news releases and social media—identifying specific locations, dates, and times where an infectious person was present, says Darcy Phelan-Emrick, DrPH ’09, MHS ’05, an associate scientist in Epidemiology.  

These alerts are designed to halt or prevent potential outbreaks. A legitimate measles alert will come from official public health sources, such as local or state health departments or the CDC, and should include these elements:  

The Context of the Exposure 

Where and when: Alerts should list specific locations (e.g., stores, schools, airport terminals) visited by an infectious individual, as well as precise dates and time ranges when the person was in that location (e.g., “Tuesday, February 10, between 2 p.m. and 6 p.m.”).  

Explanation of transmission risk: Measles is spread from person to person, commonly transmitted through close contacts—through droplets when a person coughs or sneezes, for example—and is inactivated by ultraviolet light and heat. But “it can remain infectious while suspended in the air, or survive on surfaces, for up to two hours,” says William Moss, MD, MPH, executive director of the International Vaccine Access Center and a professor in Epidemiology.  

Public Health Information 

Contact details: Alerts should include direct phone numbers for local health departments for reporting symptoms or questions. “It’s important to remember,” Phelan-Emrick says, that “an alert is precautionary, and it's not a reason to panic.” 

Authority source: There should be clear identification of the health department issuing the alert, typically denoted by a header or logo.  

Method and response: “After a suspected measles case is reported to either the local or state health department, they start to gather data and investigate, reconstructing where the person was during their infectious period,” Phelan-Emrick says. Health departments find other potentially infectious individuals after measles exposure through rapid contact tracing, collaborating with health care providers, and reviewing patient logs. Departments also use other records, like school attendance and transportation rosters, to identify and contact exposed individuals.  

“If a person with measles was in a public setting during the infectious period, and the health department can't reach all the individuals who were exposed, they would then issue a public alert, because susceptible individuals need to be treated either with the MMR vaccine or immunoglobulin quickly to prevent development of illness,” Phelan-Emrick says. 

Alerts are sometimes issued days after the event. “It depends on how fast the infectious person seeks care, and how quickly the public health system can respond with lab confirmation, investigation, and contact tracing,” says Phelan-Emrick. 

To stay up to date with these kinds of alerts, “subscribe to press releases from both state and local health departments near you, and keep an eye on the news,” says Phelan-Emrick. Measles tracking tools are also available on many public health authorities’ websites. 

What to Do After Possible Exposure 

Check immunity status: “The most important thing people can do after seeing a measles alert is to immediately verify their MMR vaccination status and, if unvaccinated or unsure, call their health care provider or local public health department for guidance,” says Moss.  

Two doses of the measles vaccine provide 97% lifelong protection against the disease, and one dose provides 93% protection. People born before 1957 are also protected, “because almost everyone born before that year was exposed to wild type measles virus,” Moss says. (Measles vaccines were not available until 1963.) 

If a person cannot find documentation of their vaccination status, “the easiest thing to do is to get a measles vaccine,” Moss says. “It's inexpensive and it's safe.”  

There’s no harm in getting an extra MMR dose “just in case,” he says. “If someone does not have protective immunity against measles, it will definitely help them. If they already have existing protective immunity, it won't be harmful.” 

There are tests to measure immunoglobulin G (IgG) antibodies, the protective antibodies against measles that are induced by vaccination. But, Moss says, “many commercially available tests aren't sensitive enough to determine immunity. It's easier to just get the vaccine.” 

Isolation: For unvaccinated individuals, there is a quarantine period after measles exposure, Moss says. This period begins five days after first exposure and ends the twenty-first day after last exposure. The interval is extended to 28 days if immunoglobulin is administered, as it can prolong the incubation period.  

Except in health care settings, unvaccinated individuals who receive their first dose of MMR vaccine within 72 hours of exposure do not have to quarantine and can return to childcare, school, or work, Moss says. 

If a child's school reports a measles exposure, Moss says “the main thing parents need to do is make sure that their child is fully vaccinated with two doses of measles vaccine.” 

Contact protocols: If you believe you were exposed and are seeking health care in person, call your doctor, urgent care, or ED before visiting. This allows them to prepare for your arrival and take precautions to not infect others in the waiting room, says Phelan-Emrick. 

Post-exposure prophylaxis (PEP) for unvaccinated individuals: Up to 90% of unvaccinated people close to an infectious person will get measles. “You can give the MMR vaccine within 72 hours of exposure,” says Moss. “While it may not completely prevent the illness, it will reduce its severity.” Within six days of exposure, an individual may be eligible for immunoglobulin, which can also reduce risk and severity.  

Children under 5 years old, pregnant women, and immunocompromised people (either through an underlying health condition or due to medical treatment) are at the greatest risk for measles complications, Phelan-Emrick says. 

Symptoms to Watch For 

Measles symptoms begin to appear 7 to 21 days after exposure and generally follow this timeline:  

• 7–14 days after initial infection: The earliest symptoms of measles appear, including fever and the three Cs—cough, coryza (runny nose), and conjunctivitis (red eyes).
• 2–3 days after symptoms begin: Koplik spots, small white bumps with a red halo, appear on the inner side of the mouth before the onset of rash. They are a disease-specific sign for measles, but are often missed, because “a clinician has to really be looking for them,” Moss says.
• 3–5 days after symptoms begin: The characteristic measles rash, flat red spots originating near the hairline, emerges. The rash spreads to the neck, abdomen, arms, legs, and feet. “People with measles are most contagious for about three to four days before the rash appears, and three to four days after the rash,” says Moss.  

If someone in your household who has measles rapidly gets worse, or has symptoms like trouble breathing, pain when coughing, dehydration, fever or headache that will not go away, confusion, or blue color around the mouth, the CDC recommends that you take them to a hospital emergency department immediately. Remember to notify the hospital before arrival so they can be prepared to isolate the patient.