Measles is making a comeback: Can we stop it?

Has the recent news about measles outbreaks in the US surprised you? Didn't it seem like we were done with measles?

In the US, widespread vaccination halted the ongoing spread of measles more than 20 years ago, a major public health achievement. Before an effective vaccine was developed in the 1960s, nearly every child in the US got measles. Complications like measles-related pneumonia or hearing loss were common, and 400 to 500 people died each year.

As I write this, there have been 164 confirmed cases in nine states, mostly among children. The biggest outbreak is in west Texas, where more than 20 people have been hospitalized and an unvaccinated school-aged child recently died, the first measles death in the US since 2015.

Can we prevent these tragedies?

Measles outbreaks are highly preventable. It's estimated that when 95% of people in a community are vaccinated, both those individuals and others in their community are protected against measles.

But nationally, measles vaccination rates among school-age kids fell from 95% in 2019 to 92% in 2023. Within Texas, the kindergarten vaccination rates have dipped below 95% in about half of all state counties. In the community at the center of the west Texas outbreak, the reported rate is 82%. Declining vaccination rates are common in other parts of the US, too, and that leaves many people vulnerable to measles infections.

Only 2% of the recent cases in the US involved people known to be fully vaccinated. The rest hadn't received vaccines, or their vaccination status wasn't known.

What to know about measles

As measles outbreaks occur within more communities, it's important to understand why this happens — and how to stop it. Here are seven things to know about measles.

The measles virus is highly contagious

Several communities have suffered outbreaks in recent years. The measles virus readily spreads from person to person through the air we breathe. It can linger in the air for hours after a sneeze or cough. Estimates suggest nine out of 10 nonimmune people exposed to measles will become infected. Measles is far more contagious than the flu, COVID-19, or even Ebola.

Early diagnosis is challenging

It usually takes seven to 14 days for symptoms to show up once a person gets infected. Common early symptoms — fever, cough, runny nose — are similar to other viral infections such as colds or flu. A few days into the illness, painless, tiny white spots in the mouth (called Koplik spots) appear. But they're easy to miss, and are absent in many cases. A day or two later, a distinctive skin rash develops.

Unfortunately, a person with measles is highly contagious for days before the Koplik spots or skin rash appear. Very often, others have been exposed by the time measles is diagnosed and precautions are taken.

Measles can be serious and even fatal

Measles is not just another cold. A host of complications can develop, including

• brain inflammation (encephalitis), which can lead to seizures, hearing loss, or intellectual disability
• pneumonia
• eye inflammation (and occasionally, vision loss)
• poor pregnancy outcomes, such as miscarriage
• subacute sclerosing panencephalitis (SSPE), a rare and lethal disease of the brain that can develop years after the initial measles infection.

Complications are most common among children under age 5, adults over age 20, pregnant women, and people with an impaired immune system. Measles is fatal in up to three of every 1,000 cases.

During the latest outbreaks, about one in five cases has required hospitalization.

Getting measles may suppress your immune system

When you get sick from a viral or bacterial infection, antibodies created by your immune system will later recognize and help mount a defense against these intruders. In 2019, a study at Harvard Medical School (HMS) found that the measles virus may wipe out up to three-quarters of antibodies protecting against viruses or bacteria that a child was previously immune to — anything from strains of the flu to herpesvirus to bacteria that cause pneumonia and skin infections.

"If your child gets the measles and then gets pneumonia two years later, you wouldn't necessarily tie the two together. The symptoms of measles itself may be only the tip of the iceberg," said the study's first author, Dr. Michael Mina, who was a postdoctoral researcher in the laboratory of geneticist Stephen Elledge at HMS and Brigham and Women's Hospital at the time of the study.

In this video, Mina and Elledge discuss their findings.

Vaccination is highly effective

Two doses of the current vaccine provide 97% protection — much higher than most other vaccines.  Rarely, a person gets measles despite being fully vaccinated. When that happens, the disease tends to be milder and less likely to spread to others.

The measles vaccine is safe

 The safety profile of the measles vaccine is excellent. Common side effects include temporary soreness in the arm, low-grade fever, and muscle pain, as is true for most vaccinations. A suggestion that measles or other vaccines cause autism has been convincingly discredited. However, this often-repeated misinformation has contributed to significant vaccine hesitancy and falling rates of vaccination.

Ways to protect yourself from measles infection

• Vaccination. Usually, children are given the first dose around age 1 and the second between ages 4 and 6 as part of the Measles-Mumps-Rubella (MMR) vaccine. If a child — or adult — hasn't been vaccinated, they can have these doses later.
  
  If you were born after 1957 and received a measles vaccination before 1968, consider getting revaccinated or tested for measles antibodies (see below). The vaccine given before 1968 was less effective than later versions. And before 1957, most people became immune after having measles, although this immunity can wane.
• Isolation. To limit spread, everyone diagnosed with measles and anyone who might be infected should avoid close contact with others until four days after the rash resolves.
• Mask-wearing by people with measles can help prevent spread to others. Household members or other close contacts should also wear a mask to avoid getting it.
• Frequent handwashing helps keep the virus from spreading.
• Testing. If you aren't sure about your measles vaccination history or whether you may be vulnerable to infection, consider having a blood test to find out if you're immune to measles. Memories about past vaccinations can be unreliable, especially if decades have gone by, and immunity can wane.
• Pre-travel planning. If you are headed to a place where measles is common, make sure you are up to date with vaccinations.

The bottom line

While news about measles in recent months may have been a surprise, it's also alarming. Experts warn that the number of cases (and possibly deaths) are likely to increase. And due to falling vaccination rates, outbreaks are bound to keep occurring. One study estimates that between nine and 15 million children in the US could be susceptible to measles.

But there's also good news: we know that measles outbreaks can be contained and the disease itself can be eliminated. Learn how to protect yourself and your family. Engage respectfully with people who are vaccine hesitant: share what you've learned from reliable sources about the disease, especially about the well-established safety of vaccination.