Measles vaccination: Know the facts

Inhaled corticosteroids may help with inflammation from complications like asthma or wheezing triggered by measles — but only under medical supervision.

Clarithromycin only treats bacterial infections. Measles is caused by a virus. Antibiotics don’t work against it — they work only for treating secondary bacterial infections. Taking antibiotics for measles can cause side effects and cannot help with measles.

Vitamin A can reduce complications in malnourished children who have vitamin A deficiency. It might reduce complications in well-nourished children, but no one knows for sure. We do know that too much vitamin A can be dangerous. Vitamin A treatment as part of supportive care for severe cases of measles should only be done with the supervision of a health care professional. Learn more.

Measles is a serious illness that can hospitalize 1 in 5 patients, cause permanent brain damage and kills 1-2 out of every thousand people who catch it.

There is no evidence that the MMR vaccine causes autism, and there is a great deal of evidence that shows it does not cause autism. Many studies have found there is no connection between the two, including research that tracked more than 650,000 Danish children and found the MMR vaccine “does not increase the risk for autism, does not trigger autism in susceptible children and is not associated with clustering of autism cases after vaccination.”

In the U.S., more than 2,000 cases of measles were reported in 2025, the most number of cases since measles was declared eliminated in the U.S. in 2000. Even after a disease has been eliminated from a country, outbreaks can still happen when measles is brought into the country by unvaccinated travelers — in the U.S., this includes both U.S. residents who travel internationally and return to the U.S. and people from other countries who visit this country.

U.S. residents, as opposed to foreign visitors, accounted for 62% of imported measles cases in the U.S. from 2001 to 2016. There have been numerous local and regional measles outbreaks coast to coast in recent years. These outbreaks would be far worse if the majority of Americans weren’t vaccinated.

Ensuring vaccination rates stay above 95% decreases the likelihood of measles spreading among those who aren’t vaccinated. This is called herd immunity, which provides protection for people who can’t receive the vaccine, such as infants who aren’t old enough and people with a weakened immune system, such as people with HIV or cancer.

When local vaccination rates are lower than needed for herd immunity, those areas can experience outbreaks if measles is introduced to the community, most often when someone gets measles in a country where the disease is more common and travels to the U.S. That’s what we’ve been seeing in recent years. And considering measles is highly contagious, these outbreaks spell trouble. In fact, up to 9 out of 10 people who aren’t immune and are exposed will get it, making it much more contagious than the flu and one of the most contagious diseases known to science.

While better sanitation (clean water, for example) has decreased the rates of diseases spread through food or water (such as cholera and typhoid), it has a minimal effect on measles, which is spread person to person and through the air. After the measles vaccine was introduced in 1963, reported cases dropped by more than 97% between 1965 and 1968, despite the fact that hygiene practices and sanitation did not significantly change during that time.

The measles vaccine prevents thousands of deaths each year worldwide. The number of measles deaths began decreasing before the vaccine was introduced thanks to advances in health care that improved treatment after people got sick (such as treating pneumonia that occurred because of measles infection). But serious illness and death from measles still happened regularly. In fact, in the 10 years before the vaccine was available in 1963, about 500 measles-related deaths were reported to CDC every year. 

Since the vaccine, U.S. measles-related deaths have been rare — because the vaccine has prevented people from getting measles in the first place. In 2025, three people died from measles in the U.S., the first reported measles deaths in the country since 2015. Worldwide, there was an 84% decrease in measles deaths between 2000 and 2016 as the vaccine became more widely available — meaning more than 20 million deaths were prevented.

Other than death, measles causes serious illness and leads to hospitalization for 1 in 5 who become sick. That’s why it’s important to look at the reduction in measles cases overall, which plummeted after the vaccine was introduced in 1963 — from about 500,000 reported cases yearly (most weren’t reported, so the actual number is likely much higher) to 63 reported cases in 2010. Recently, those numbers have been increasing due to local outbreaks.

There have been no deaths shown to be related to the MMR vaccine in healthy people. There have been rare cases of deaths from vaccine side effects among children who are immune compromised, which is why it is recommended that they don’t get the vaccine. That’s why it is so important that everyone who can get vaccinated does so, to protect those who can’t. Like any vaccine, MMR can cause side effects, including a sore arm (from the shot), fever, mild rash or temporary pain/stiffness in the joints. These side effects are usually mild and go away within a day or two. There is also a very small risk of febrile seizures (which do not have any long-term effects) or an allergic reaction. Vaccines undergo a scientifically rigorous research and vetting process before they are approved.

There is no evidence that there is any benefit to separating the combination MMR vaccine (measles, mumps and rubella) into three individual shots. Getting multiple vaccines at once has been shown to be safe and does not cause any long-term health problems. Babies and children are exposed to thousands of germs in the environment from the time they are born, and receiving more than one vaccine at a time does not overload their immune systems. Children should get their vaccines at the recommended time to give them protection during their early years when they are vulnerable to infection and allows fewer office visits, which can be easier for parents and children.

The MMR is a weakened live virus vaccine, also known as an attenuated vaccine. Because it has been weakened, it cannot cause an actual measles illness. Theoretically, someone who has received the MMR vaccine could shed small amounts of this weakened virus, but there has never been a case of anyone getting measles from someone who got the vaccine. MMR vaccine is even safe to give to people who live with someone with a weakened immune system who cannot receive live vaccines. Because their immune system is working hard after vaccination, some children who get the vaccine can have mild symptoms such as a fever or rash, but it’s not measles — it’s just the body building immunity to the measles virus so that they don’t get sick if they’re ever exposed. 

Rarely, vaccine-associated measles can occur in people with compromised (weakened) immune systems, such as people receiving chemotherapy or who have received transplants. That is why the MMR vaccine is not recommended for immune-compromised individuals or those who are pregnant. This is why it is so important for everyone else to get vaccinated, as it protects those individuals who cannot receive the vaccine or who are too young to receive the vaccine.