Measles Cases Are Rising Again in the U.S.: What to Know About Risk, Vaccination, and Prevention

Measles, once declared eliminated in the United States in 2000, has made a troubling comeback in recent years. The Centers for Disease Control and Prevention (CDC) has reported increases in measles cases and outbreaks in multiple states, often linked to undervaccinated communities and international travel.

For most families, the key takeaway is straightforward: measles is highly contagious, but it is also preventable with vaccination. Understanding how it spreads, who is at risk, and when to seek care can help protect both individuals and communities.

Why Measles Is Back in the Headlines

Measles spreads easily through the air when an infected person coughs or sneezes. According to the CDC, the virus can linger in the air for up to two hours after an infected person leaves a room. About 9 out of 10 unvaccinated people who are exposed will become infected.

Although overall vaccination coverage in the U.S. remains high, even small declines in measles-mumps-rubella (MMR) vaccination rates can create pockets of vulnerability. When vaccination levels drop below the threshold needed for community protection—often called herd immunity—outbreaks can occur.

Recent outbreaks have often been linked to:

Communities with lower vaccination rates
Delays in routine childhood immunizations
International travel to countries where measles remains common

The World Health Organization (WHO) has also reported global increases in measles activity in recent years, which raises the risk of imported cases into the U.S.

What Are the Symptoms of Measles?

Measles symptoms typically appear 7 to 14 days after exposure. Early symptoms can look like a common viral illness, which makes early detection challenging.

Common symptoms include:

High fever
Cough
Runny nose
Red, watery eyes
Small white spots inside the mouth (Koplik spots)
A red rash that usually starts on the face and spreads downward

The rash generally appears a few days after the fever begins. People are contagious from about four days before the rash appears to four days after.

Who Is Most at Risk?

Anyone who is not protected by vaccination or prior infection can get measles. However, certain groups face higher risk of severe illness:

Infants too young to be vaccinated (under 12 months)
Pregnant people without immunity
People with weakened immune systems
Unvaccinated children and adults

Complications can include pneumonia, ear infections, diarrhea, and in rare cases, brain swelling (encephalitis). According to the CDC, measles can be especially serious in young children.

How Effective Is the MMR Vaccine?

The MMR vaccine is a well-studied, long-standing vaccine recommended by the CDC and the American Academy of Pediatrics (AAP). Two doses are about 97% effective at preventing measles; one dose is about 93% effective.

The routine schedule in the U.S. is:

First dose at 12–15 months of age
Second dose at 4–6 years of age

Most adults born after 1957 should have documentation of at least one dose unless they have other evidence of immunity. Certain adults—such as healthcare workers or international travelers—may need two documented doses.

Like all vaccines, the MMR vaccine can cause mild side effects such as fever or soreness at the injection site. Serious adverse reactions are rare, according to the CDC and extensive post-licensure safety monitoring.

What Parents and Adults Should Do Now

If you are unsure about your or your child’s vaccination status, check with your healthcare provider or state immunization registry. Catch-up vaccination is available and recommended for those who are not up to date.

Before international travel, especially with young children, review CDC travel health notices. In some cases, infants 6–11 months old may receive an early dose if traveling to areas with active measles transmission.

If you think you or your child has been exposed to measles:

Call your healthcare provider before going to a clinic or emergency room so they can prepare to prevent further spread.
Monitor for fever and rash.
Follow local public health guidance.

Community Impact: Schools, Workplaces, and Healthcare Access

Outbreaks can disrupt schools and childcare settings, leading to temporary exclusions for unvaccinated students during exposure periods. Employers may also face workforce disruptions if employees become ill or must quarantine.

From a public health standpoint, measles outbreaks require significant resources for contact tracing and containment. This can strain local health departments, especially in communities with limited funding.

Vaccination remains one of the most effective tools for preventing these disruptions. High community coverage protects infants, people with medical exemptions, and others who cannot be vaccinated.

What This Means for Readers

Measles is not just a childhood illness from the past—it is a real and preventable infection that can resurface when vaccination coverage slips.

For most families, the action steps are practical:

Confirm that children are up to date on the MMR vaccine.
Check your own immunization history.
Follow public health guidance during outbreaks.
Talk with a licensed clinician if you have questions about vaccine safety or timing.

Staying informed and up to date on vaccination helps protect not only your household but also your wider community.

This article is for general informational purposes only and is not medical advice. Research findings can be early, limited, or subject to change as new evidence emerges. For personal guidance, diagnosis, or treatment, consult a licensed clinician. For current outbreak or public health guidance, follow your local health department, the CDC, or another relevant public health authority.

Sources

Centers for Disease Control and Prevention (CDC) – Measles (Rubeola)
World Health Organization (WHO) – Measles Fact Sheets and Global Updates
American Academy of Pediatrics (AAP) – Immunization Guidance