Measles outbreak: What experts need Ohioans to know about the MMR vaccine

As the U.S. continues to battle the largest spike in measles cases since 2019, experts underscore the importance of MMR vaccinations to prevent the spread of measles and bolster collective immunity.

Measles is a highly infectious, life-threatening viral disease that infects the respiratory tract. Before the measles vaccine was introduced in 1963, it is estimated that 3 to 4 million people in the U.S. contracted measles every year, causing 500 deaths and 48,000 hospitalizations annually, according to the U.S. Centers for Disease Control & Prevention. 

The MMR vaccine, a combination vaccine that protects against measles, mumps and rubella, has been instrumental in curtailing the spread of measles. The vaccine has been available in its current form since 1971, marking more than 50 years of safe and effective use.

What is the MMR vaccine?

The MMR vaccine is an attenuated vaccine, meaning it uses particles of live viruses to help generate the body's immune response and build antibodies, says Dr. Matthew Harris, a pediatric emergency medicine physician and medical director of clinical preparedness for Northwell Health. “Everyone is encouraged to get it, because as we've seen in Texas and New Mexico, measles spreads like wildfire,” says Harris. 

The MMR vaccine is highly effective. Most vaccinated people will not develop measles, mumps or rubella when they are exposed to the diseases. But, in the case a vaccinated person does develop one of these diseases, their symptoms are typically milder, and they are far less contagious, per the CDC.

Is the MMR vaccine safe?

The MMR vaccine is very safe, says Harris. For decades, the vaccine has been administered to millions of children, helping to prevent severe and life-threatening complications of measles, mumps and rubella. Serious side effects of the vaccine, including seizures, are rare. 

Over the years, multiple large-scale studies have debunked claims linking the MMR vaccine and autism. Studies have also disproven connections between autism and vaccines containing thimerosal, a preservative often used in combination vaccines, according to the U.S. Food & Drug Administration.

When should you receive the MMR vaccine?

The MMR vaccine is administered in two doses, usually during childhood. One dose provides 93% protection against measles, and two doses provide 97% protection, says Dr. Peter Chin-Hong, a professor of medicine and infectious disease specialist at UCSF Health. When you receive two doses of MMR, you are considered to be fully immunized against measles.

Healthcare providers prioritize administering the MMR vaccine during early childhood for two primary reasons, Harris says. First, measles, mumps and rubella are highly infectious, and spread easily in congregant settings, such as daycares and summer camps. Second, children are particularly vulnerable to developing severe symptoms. Unvaccinated children under the age of 5 have an elevated risk of experiencing dangerous complications due to measles, including pneumonia, encephalitis (brain inflammation), loss of sight or hearing and death, per the CDC.

It is recommended that babies receive their first dose of the MMR vaccine when they’re between 12 and 15 months. The second MMR dose is usually administered when a child is 4 to 6 years old. In the case of a measles outbreak, or international travel, a baby can receive one dose of MMR when they are as young as six months old. They will still need to receive another two doses of the vaccine within the CDC-recommended time frames after they turn 1, says Chin-Hong. 

If you weren’t vaccinated against measles as a young child, you can still receive the MMR vaccine later in life, note Chin-Hong and Harris. Two doses of MMR will yield the same level of protection against measles, even if you’ve previously been exposed to the disease. It’s important to note certain groups of people, including pregnant women and some immunocompromised individuals, aren’t able to receive the MMR vaccine. This is the minority of patients, and a healthcare provider can help determine your eligibility for the vaccine.

If you’re unsure whether you’re protected against measles, check your vaccination records. It’s possible some individuals may need to be revaccinated, although this isn’t the case for most people. For example, if you find you were vaccinated between 1963 and 1967 and received the killed measles vaccine, the CDC recommends you receive at least one dose of a live attenuated measles vaccine.