By Teddy Amenabar

At least 62 people with measles have traveled on planes this year, and one person became infected. But being fully vaccinated can help protect you.

People with measles, a highly contagious disease, are traveling on airplanes, raising concerns about the spread of the respiratory virus as global cases rise and summer travel season gets underway in the United States.

The Centers for Disease Control and Prevention is warning that people can get infected with measles during travel or at crowded events, unless they are fully vaccinated or have had the disease.

“Travelers can catch measles in many travel settings, including travel hubs like airports and train stations, on public transportation like airplanes and trains, at tourist attractions, and at large, crowded events,” the CDC said in its updated advisory Tuesday.

For those planning summer travel or going to concerts, getting vaccinated is the best way to stay safe, the CDC and health-care experts say.

“If you’re fully vaccinated against measles, this is not something I think you have to put on your worry list this summer,” said Jennifer Nuzzo, the director of the Pandemic Center at the Brown University School of Public Health.

Here’s what to know about the advisory, how measles is spread and how you can protect yourself.

What does the CDC’s updated advisory say?

The agency has received 62 reports of people with measles traveling on airplanes since the beginning of the year, a spokesperson said. It has investigated 50 cases of travelers flying into the U.S. or domestically and found “only one situation” in which measles appeared to have been transmitted during air travel, the spokesperson said in an email.

The U.S. is experiencing the biggest outbreak of measles since 2020. As of Thursday, 1,088 confirmed measles cases and three confirmed deaths have been reported by 32 states, according to the CDC.

“We are on track to have, perhaps, one of the worst measles years that we’ve had in the last 25 years since we eliminated measles,” Nuzzo said.

The agency recommends that all international travelers, including infants 6 to 11 months old, get the measles, mumps and rubella, or MMR, vaccine if they do not have proof of immunity, because it provides the best defense against the highly contagious virus. Most people in the U.S. have gotten these shots as children, but a measles vaccine booster may help some adults.

“Most people who bring measles into the United States are unvaccinated U.S. residents who get infected during international travel,” the CDC said in its advisory.

How does measles spread?

Measles is one of the most infectious diseases, Nuzzo said. It can be severe for individuals at any age and can lead to life-threatening complications such as pneumonia and even death. A rash — usually the telltale sign of infection — high fever, cough, runny nose and red, watery eyes are some common symptoms of measles.

One of the reasons the highly contagious virus can spread is because, at first, the infection can look like the common cold or another respiratory illness, said William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health.

Infected individuals can spread measles up to four days before or after their rash begins, the CDC says.

The virus is spread through coughing and sneezing, and it can live for up to two hours in the air or on surfaces, the CDC says. “It travels through larger droplets when we sneeze or cough, and the virus can stay suspended in the air for one or two hours floating in smaller droplets,” said Moss, also a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

You can get infected if you breathe the contaminated air or touch the infected surface and then touch your eyes, nose or mouth, the CDC says.

How should I protect myself before traveling?

The MMR vaccine is the best protection against the measles virus, health-care experts said. The vaccine also guards against mumps and rubella.

But there’s evidence that vaccination rates are decreasing in some parts of the U.S. Since the pandemic, there’s been a widespread decline in MMR vaccination rates of children, according to a letter published Monday.

Children could get the measles, mumps, rubella and varicella (MMRV) vaccine, which also protects against chicken pox, the CDC said.

The agency recommends that infants 6 to 11 months old get one dose of the MMR vaccine at least two weeks before travel and two more doses after turning 1 — at 12 to 15 months and at 4 to 6 years.

“Children 12 months old and older, teenagers, and adults who are unsure of their immunity against measles should receive two doses of MMR vaccine at least 28 days apart before international travel,” the CDC said in its advisory.

What is the risk of catching measles on a plane?

It’s possible for someone to contract the virus on a plane, Nuzzo said, but she is more concerned about unvaccinated travelers who are traveling to places with ongoing measles outbreaks.

“Not to say that you can’t get it on a plane,” Nuzzo said. “But the probability of sitting next to somebody who has measles on a plane is much lower than, say, going to a place where there’s a high burden of measles.”

The risk from air travel is more about whom you’re coming in contact with in the places you’re visiting. “The act of travel itself is not particularly risky, nor is the act of even riding on an airplane,” Nuzzo said.

The air circulating through the cabin of an airplane is filtered, she said. So, the potential risk comes from sitting next to a person who’s sick with measles, not necessarily the person in a different part of the plane.

“It’s a respiratory disease,” Nuzzo said. “If you want to reduce the likelihood of becoming infected somewhere, you can wear a mask.”

If you’re worried about contracting an infection on a plane, Nuzzo said, the most important times to wear a mask are before takeoff and after landing, when the plane’s air filtration often has been turned off. “But airports and airplanes are not by themselves particularly risky,” she said.

Nuzzo said she does not wipe down surfaces when she is on a plane. “I think the surfaces are sometimes gross, and I’ve often wished I had a wipe, but I’m not scared enough to travel with them,” she said. “It’s really about your risk tolerance.”

What about airport terminals?

People have been infected in airport terminals. In 2014, four unvaccinated individuals who passed through the same U.S. airport terminal contracted measles. “The exposures in this report were not prolonged and occurred in a domestic rather than an international terminal,” according to a report published by the CDC.

“We don’t need folks to panic about going outside or to public spaces,” Margot Savoy, a senior vice president at the American Academy of Family Physicians, said in an email. “But they do need to be aware that measles, once eliminated here in the U.S., is back. And though it started out only impacting small unvaccinated communities, the exposures and cases continue to rise all across the country.”

How far in advance of travel should I get vaccinated?

If you are unsure of your immunity, see your doctor at least six weeks before you travel to allow enough time to get fully vaccinated, said Scott Roberts, an assistant professor of infectious diseases at Yale School of Medicine.

Some people, including those who are pregnant, have a weakened immune system or have gotten other vaccines in the past four weeks should not get the MMR vaccine or should wait, the CDC says. “Travelers unable to safely receive a measles-containing vaccine should talk to their clinician and consider postponing their trip,” the agency advises.

Should I get a booster shot of the measles vaccine?

The answer depends on when you were born, your vaccine records and whether you plan to travel internationally.

People born before 1957 are assumed to have been exposed to measles when they were a child, Savoy said in March.

Some adults who received the vaccine between 1963 and 1967 (less than 5 percent, according to the CDC) may have received a version of the measles vaccine that isn’t as effective, Adam Ratner, the director of the division of pediatric infectious diseases at New York University Grossman School of Medicine, said in March. If you fall into that age range and you are not sure what version of the vaccine you got, the CDC recommends another dose.

People born between 1968 and 1989 possibly got one dose of the measles vaccine, instead of the two given to children today. The CDC says one dose is enough for most adults but recommends two doses of the vaccine for anyone planning international travel. And health officials may recommend that people get a second dose of the vaccine if there’s a local measles outbreak.

If you got two doses of the measles vaccine, experts said, a booster isn’t going to provide any additional protection.

A person’s vaccine-induced measles immunity can wane over time, but it’s rare, Ratner said. What can happen is “primary vaccine failure,” when a person doesn’t respond to one dose of the measles vaccine and they’re not protected against the virus, Ratner said. This is why children get a second dose, to ensure they have the antibodies, he said.

There are lab tests that can measure a person’s antibody protection against measles, Savoy said. But the test may not be covered by insurance, and the results are only an approximate measurement of a person’s risk if they are exposed to the virus, she said.

What should I do if I’m unvaccinated and have been exposed to the virus?

Getting the MMR vaccine within 72 hours of exposure can provide some protection or lessen symptoms, and does not cause harm, the CDC says. It also may prevent future disease.

A medication called immunoglobulin, taken within six days of exposure, also provides some protection against measles or helps make the illness milder, the agency says.

States with reported measles cases

Cases have been confirmed by the CDC in Alaska, Arkansas, California, Colorado, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont, Virginia and Washington state.

Globally, many countries have reported measles outbreaks, including large outbreaks in Mexico and Canada, leading the CDC to recommend “vaccination against measles before traveling to any international destination.”