During the height of the COVID-19 pandemic, the Centers for Disease Control and Prevention warned that 22.3 million infants globally missed their first dose of the measles vaccine in 2020, contributing to the largest annual increase in over 20 years of unvaccinated children in the U.S. The concern, researchers said at the time, was that it would lead to outbreaks of measles and other preventable illnesses in the future.
Now, there's a measles outbreak in central Ohio — and the majority of the children impacted are unvaccinated. According to the official city of Columbus website, there have been 85 cases of measles since the outbreak began in November 2022, and 34 people have been hospitalized with the virus. Of those affected, 78 were unvaccinated, six had only one dose of the measles, mumps and rubella (MMR) vaccine that works to prevent the illness, and one had an unknown vaccination status.
All of the cases were in children ages 17 and younger, and the vast majority of patients were ages 2 and younger.
Columbus Health Commissioner Mysheika Roberts said in an interview last month that the outbreak started with a small group of people who returned from an area where measles regularly occurs. The virus spread quickly in young, unvaccinated children. "The reason why so many of our young children have been impacted by this measles outbreak is because that's the greatest majority of our population that's unvaccinated," she said.
These aren't the only cases of measles in the U.S. over the past year: Data from the CDC shows that there were 118 cases of measles in 2022, up from 49 cases in 2021. (Data for 2023 is not yet available online.)
It's understandable to have questions about measles after this. Here's what you need to know.
What is measles?
Measles, which is caused by a virus, is an acute viral respiratory illness that leads to a range of uncomfortable symptoms, including a distinct rash, high fever and cough, per the CDC. But it's not your average illness. "Measles is a dangerous disease that has the capacity to cause pneumonia, brain infection and can erase aspects of one's immune system," Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, tells Yahoo Life. More specifically, a measles infection can damage a person's immune system by wiping out up to 73% of preexisting antibodies for other diseases, including influenza.
The virus is also "extraordinarily infectious — even more infectious than COVID," Dr. Thomas Russo, chief of infectious diseases at the University at Buffalo in New York, tells Yahoo Life.
Dr. Danelle Fisher, chair of pediatrics at California's Providence Saint John's Health Center, tells Yahoo Life that measles is so contagious, the virus can still make someone sick up to two hours after a person with measles has left a room. "This is so highly, highly contagious," she says.
How is measles transmitted?
Measles spreads in a way that's "similar to COVID," Russo says. It's transmitted through direct contact with infectious droplets or respiratory particles that get into the air when an infected person breathes, coughs or sneezes, according to the CDC. And again, the virus can linger in the air for two hours after someone with measles has left the area.
People can also get measles from touching an infected surface and then touching their eyes, nose or mouth, the CDC says.
The CDC points out that measles is so contagious that if a person has it, up to 90% of those around that person who are not immune to the virus will also become infected.
Signs of measles to have on your radar
Measles symptoms usually show up seven to 14 days after someone has been infected, according to the CDC, and symptoms tend to come in stages.
In the first stage, a child will typically experience these symptoms:
Red, watery eyes.
"Usually, you have these coldlike symptoms first," Fisher says. From there, a patient may experience tiny white spots (called Koplik spots) inside the mouth, per the CDC. Three to five days after symptoms begin, a rash usually breaks out, starting as flat red spots that appear on the face and spread down the rest of the body. Measles can also cause serious complications such as pneumonia and brain swelling, according to the CDC. "It's not a very fun disease to have," Russo says.
How to prevent measles
Measles is prevented with the two-dose MMR vaccine. The CDC recommends that children get the first dose of the vaccine when they are 12 to 15 months old and the second dose when they are 4 to 6 years old. One dose of the vaccine is about 93% effective at preventing measles, while both doses are about 97% effective, the CDC says.
It's important to point out that the majority of children impacted in the Ohio outbreak were under 2 and therefore ineligible to be fully vaccinated against measles. However, those over 12 months — the largest group affected — were eligible to receive the first vaccine in the series. Still, only six of the 85 people impacted in the outbreak had received one shot.
Herd immunity — which is when a sufficient enough portion of a population is immune to a disease that even people who aren't vaccinated are offered some protection because the disease has little opportunity to spread in the community — is important to protect those who aren't yet vaccinated, those who aren't fully vaccinated and those who are immunocompromised and won't have an optimal response to the vaccine, Russo says.
"The only means of protection is a vaccine," Fisher says. "I can't believe we're here again. This is directly linked to decreased immunizations."
How is measles treated?
There is no specific treatment for measles. Instead, children may be given acetaminophen or ibuprofen for aches, pains or fever, and encouraged to drink plenty of fluids, Russo says.
"We really don't have much in the way of treatment," he says. "The key with measles is prevention."
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