MMR vaccine: Just the basics from a mom and scientist
Have questions? Let me see if I can help.
Hi neighbors! SO many of you had questions asking about the MMR vaccine a few weeks ago when I asked how I could help. Measles was one of the top topics for you all. And, most of you are moms and dads with littles asking really good questions about the MMR vaccine and whether or not you should have your child vaccinated. As a parent of 2 teenagers (not-so-littles), I remember those days of having little kids and wanting to do the best for them. So, let me see if I can help answer your questions in this post. (For the record, both of my kids got all of their vaccines. I do remember doing lots of homework and asking our pediatrician way-too-many questions. =) So, you’re in good company!) In writing this post, I also want to tell you that I have nothing to prove or win here. I just want to be a good neighbor and share some tried-and-true facts you can trust for your own family. There’s so much noise out in the world right now, isn’t there? I get that, and I get how confusing it all can be. Let me see if I can help give some peace towards the MMR vaccine.
What is measles?
Measles is a viral infection. Once infected, it usually takes 10-14 days to become symptomatic. At the beginning (4-7 days), symptoms include a running nose, cough, eye irritation (think red and watery), and white spots inside your cheeks. The characteristic rash begins 7-18 days after exposure, spreading from the face and upper neck first, and then to the hands and feet.
Why do we need to take measles seriously?
Measle is the most infectious disease in the world.
9 out of 10 people will become infected with measles if exposed and not protected through vaccines. Measles can survive for 2 hours in the air or on infected surfaces (like doorknobs, light switches, tables, etc) and spreads when an infected person breathes, coughs, or sneezes. An infected person can transmit measles to others from 4 days prior to the rash starts. Yikes.
There is no specific treatment for measles. You’ve probably heard a lot about vitamin A being used to try to treat measles. That can actually backfire pretty bad with high levels of vitamin A leading to liver damage and toxicity.
30% of children infected with measles develop a complication. Complications include blindness, brain swelling/damage, pneumonia or other breathing problems, severe diarrhea leading to dehydration, and infections. Some of those complications can happen years after infections. 1 in 5 will need hospital care.
For pregnant women, measles can be super dangerous to her and the baby and lead to miscarriage, premature birth, and stillbirth.
How long has the MMR vaccine been around?
The first measles vaccine was licensed in 1963 after rigorous testing and trials. In 1971, a combo vaccine for measles, mumps, and rubella (MMR) was developed with a recommended two dose schedule.
Does the vaccine work?
The MMR vaccine works extraordinarily well. In fact, the vaccine is more effective at reducing cases and deaths than any other vaccine we currently have. I can’t emphasize this enough. The MMR vaccine is the top of the class when it comes to vaccines. Two doses of the MMR vaccine are ~97% effective at preventing measles. WHOA! That’s incredibly high protection against measles. Check out the impact on the next graph - prior to the MMR vaccine, the US had ~75,000 cases of measles each year. After the MMR came around, that dropped dramatically.
In the US, check out the graph below. Measles was pretty much eliminated in the US before making a comeback in 2019.
How many kids have received the MMR vaccine?
Just in the US, an estimated 31 MILLION children are vaccinated with MMR yearly. That means that hundreds of millions of children have received the MMR vaccine over the past 50 years since MMR was developed. I bring up these huge numbers to overemphasize the fact that the MMR vaccine is safe for your child. We have safety systems in place at the CDC and NIH to look for potential safety concerns when vaccines are introduced. However, this has not been the case for the MMR vaccine. Time and time again with millions of children, the MMR vaccine has shown it is safe and effective. Again, I have nothing to prove or gain by telling you this. I’m just a scientist and a mom who asked these questions with my own kids.
What’s been the impact of the MMR vaccine?
Prior to the introduction of the measles vaccines, an estimated 2 million people died each year from measles around the world. So many people were dying from measles in the 1950s and 60s that the World Health Organization launched its Expanded Programme on Immunization in 1974 to combat deadly diseases that could be preventable through vaccination. Measles was the first disease targeted because of how contagious/deadly it was and also because of how well the MMR vaccine worked. Since 1974, a dramatic reduction in measles cases and deaths has occurred.
In 1980, there were 4 million confirmed cases globally. In 2022, there were 205,000.
An estimated 94 million lives have been saved from vaccination - more than any other vaccine-preventable disease to date.
Why is there so much controversy around the MMR vaccine? And, does it cause autism?
Well, there’s several reasons, but one main reason. In 1998, Andrew Wakefield and colleagues published a paper claiming that the MMR vaccine caused autism - a paper that has since been retracted due to scientific misconduct (aka. really bad and fraudulent science). In the Wakefield paper, there were only 12 children-so not enough to make such a bold conclusion.
A recent study with 657,461 children, one of the largest ever on the MMR vaccine, looked specifically at the connection between the MMR vaccine and autism. The conclusion: MMR does not cause autism. To further evaluate, researchers looked at a subgroup of children at higher risk of autism, such as having a sibling with autism, and concluded the same: MMR does not cause autism. Decades of other studies have had the same result. (Side note: The journals that published these two studies I just linked are some of the highest and most respected scientific journals. They are very hard to get published in because of the rigorous standards of excellent science. In other words, they are as legit as they come.) Study after study after study debunked those claims.
The real data with hundreds of thousands of children show that MMR vaccines are safe and effective against measles.
What’s the current status of the US measles outbreak?
So far this year, there have been 800 reported cases of measles in the US. I, and every other scientist I trust, think this is a gross underestimation of the true case count - those of you ‘on the ground’ and managing these epidemics have told me that many people are not getting counted because they aren’t coming in for testing. So, the 800 is likely the tip of the iceberg. If you scroll up a bit and look at the map of cases in 2019, you can see there were ~1,000 by mid-June. In 2025, we are at 800 in April. Hence, this is not a normal year and cases are much higher this year than we typically see.
Should you be worried?
With the current measles case counts in the US being so high and the high likelihood that many more cases are not being counted, I am assuming (for myself and my family) that measles will spread to most of the country this year if it is not in your state already. Let me show you why - the map below shows the percentage of kindergartners vaccinated with MMR for all states. For herd immunity to act as a protective bubble against measles, we need more than 95% vaccine coverage for those kids. (This is high at 95% because measles is so contagious - remember that every person infected can infect 10-12 others. If you or your kiddos aren’t vaccinated, there’s a 90% chance of getting the measles. yikes!)
Ok, back to the map. There are only 11 states with >95% of kindergartners vaccinated with MMR. ALL other states are below that threshold, with many states below 85%. I know the difference between 85% to 95% doesn’t seem like a big deal - but, with measles it is a huge deal because of how contagious it is. We need the 95% coverage to keep our communities and children and high-risk-friends and babies and pregnant moms safe.
A final word from me.
I know many of you reading this live in areas where vaccines are a hot topic. I get that and remember being there too when my kids were small. Can I just encourage you for a minute like we were having coffee at my own kitchen table? The MMR vaccine is one of the biggest scientific successes we have had in the last one hundred years (along with the polio vaccine and mRNA, in my opinion). It has had decades of data on millions of children to show us that it is safe and it works. (And that statement is not hyperbole or an overreaction. It’s 70 years of data.) A measles infection is nothing to mess around with. The scariest part for me when my kids were little was knowing that a measles infection could be mild but then show up with severe complications years later. In other words, it can lie dormant for years (average of 7-11 years) and then land your kid in the hospital with neurological damage and a high risk of death. I didn't want to chance that or the other awful outcomes a measles infection can cause in children. I also remember wanting to protect myself after my first child was born and we were trying for another baby. Measles can be so scary during pregnancy for both the mom and the child - but especially for the child with a high risk of miscarriage or stillbirth. The MMR vaccine is safe and your greatest defense for you and your family against these very real outcomes. I have no doubt you love your kiddos as much as I love mine, and I hope I could help answer some of your questions. I wish I could also bring you some coffee and candy! =)
-Emily
PhD, MSPH in Epidemiology
Mom of 2 Teenagers. Loves being a pastor’s wife, hammocks, books, coffee, and dogs. Trying to become a bird watcher.
Thank you for all your information! I'm so grateful to have this as a resource during these confusing times. I was wondering if you had any information on the efficacy of the MMR vaccine at 6 months? I know it is being offered in some cases to babies in high risk areas. We are not currently in a high risk area but my baby is only 4 months currently so I forsee the virus spreading to our state soon (if not already). We had plans to travel this summer so wondering if the vaccine at 6 months is a viable option? Thank you in advance!
Emily, thank you for your very relatable explanation.
I would add, acute measles result in approximately 70% loss of natural/vaccine memory... immune amnesia
This results in those who were infected being susceptible to a long list...not all...various bacteria/viruses for which there is no recognition upon re-exposure.
Granted, the estimated 1:10,000 who recover & succumb to a 2nd measle's infection as a result of dormant virus sequestered in the brain tissue, the outcome is fatal...SSPE
The latter statistic is granted rare yet a compounded tragedy for parents upon living the initial illness.
JJF Phm 🇨🇦