Measles is a highly contagious viral infection that frequently causes a severe flu-like illness accompanied by a rash. Complications occur in 3 in 10 who get measles, and young children are especially vulnerable.1 Ear infections and diarrhea are the most common, but as many as 1 in 20 will get pneumonia; about 1 in 1,000 will have brain swelling that can cause deafness and intellectual disability; and nearly 3 in 1,000 will die.2 Before the vaccine was available in 1963, nearly every child got measles by age 15.3 The disease sickened 3 million to 4 million people and led to about 500 deaths and 48,000 hospitalizations every year.3
Due to a highly effective vaccination program, measles was declared eliminated from the U.S. in 2000, a historic public health achievement. However, outbreaks related to vaccine hesitancy have been occurring worldwide in recent years.4
The Infectious Diseases Society of America is committed to helping parents understand that the vaccine that prevents measles, mumps and rubella, or MMR, is safe, effective and vital to public health. The MMR vaccine typically is given to children in two doses, one between 12 and 15 months old and the second between 4 and 6 years old. Two doses of MMR vaccine in childhood are about 97% effective at preventing measles, providing long-term and possibly lifelong immunity. To help you feel confident about vaccinating your child, IDSA shares the following key facts:
There is no evidence that the MMR vaccine causes autism, but 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.”5
In 2019, the United States experienced the greatest number of measles cases reported since the disease was eliminated from this country in 2000.6 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 2016.7 There have been numerous local and regional measles outbreaks coast to coast in recent years.6 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.8 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 individuals 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.9
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.10, 11, 12
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.13 In fact, in the 10 years before the vaccine was available in 1963, about 500 measles-related deaths were reported to CDC every year.3 Since the vaccine, U.S. measles-related deaths have been increasingly rare — because the vaccine has prevented people from getting measles in the first place. The most recent U. S. death occurred in 2015.14 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.15
Other than death, measles causes serious illness and leads to hospitalization for 1 in 5 who become sick.16 That’s why it’s important to look at the reduction in measles illness 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 2010.6, 17 Recently, those numbers have been increasing due to local outbreaks.6
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.18 That’s why it is so important that everyone who can get vaccinated does so, to protect those who can’t. There are possible side effects from the vaccine, including a sore arm (from the shot), fever, mild rash, temporary pain/stiffness in the joints and a very small risk of febrile seizures or allergic reaction.19 Vaccines undergo a scientifically rigorous research and vetting process before they are approved.
While the vaccine is made from a live virus, it is weakened so that it doesn’t cause the disease, but rather causes your immune system to recognize the virus and develop immunity to it.20 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.