Immunisation
Severe or disputed reactions to the MMR vaccine
Most children who have the MMR vaccine do not have any problems with it, or if reactions do occur, they are usually mild (see 'No Reaction to MMR').
A majority of parents believe in immunisation for their children, but also included here are the views of a few parents who did not believe immunisation was right for their child based on their own personal beliefs. Their views represent a proportion of the population.
Severe reactions to the MMR vaccine
Like any medicine, a vaccine is occasionally capable of causing serious problems. We know that these problems are extremely rare. For example, severe allergic reactions (anaphylaxis) occur in less than 1 out of every million children (Oxford Vaccine Knowledge, 16 February 2024).*
Several other problems have been reported to occur after a child gets the MMR vaccine. However, as these problems can happen for other causes, and also occur in non-immunised children, it is rarely possible to know if the vaccine caused the problem in an individual child. These are sometimes referred to as disputed reactions.
One way in which experts find out whether a vaccine causes a problem is to carry out studies of whole populations to see if the risk of severe problems is commoner in children who have or have not been immunised. Before making a decision, parents and professionals need also to know about problems from the disease and balance these against any risk from immunisation (see 'Parents' views of the diseases being immunised against').
Disputed reactions to the MMR vaccine
In 1998, research by Wakefield et al. suggested a possible link between the MMR vaccine, inflammatory bowel disease and autism. Since 1998, these research findings have been discredited by many other scientific studies, which have produced verifiable scientific evidence to suggest there is no link between MMR, inflammatory bowel disease and autism.
The study by Wakefield et al. was based on only 8 children, with speculative findings that have now been discredited by most of the team that produced it and by the editor of the Lancet.
However, a very small number of parents of children who had developed severe symptoms at the same time that their child received the MMR vaccine contest these findings and have a strong personal belief that MMR triggered these symptoms in their child.
Parents talked about the symptoms that their children had shortly after their MMR vaccine and why they believed their child's symptoms were triggered by the MMR vaccine.
Experiences with disputed reactions to the MMR vaccine
One mother explained that her 8-year-old son had received his MMR vaccine when he was 13 months old, and a couple of hours afterwards he developed an agitation which lasted a couple of weeks, after which he had several petit mal epileptic episodes and stopped making any attempt to speak.
He was diagnosed as having viral encephalitis. As he got older, he was also diagnosed with autism and epilepsy.
Her son was agitated and started having petit mal epilepsy after his MMR vaccine and was diagnosed with viral encephalitis.
Her son was agitated and started having petit mal epilepsy after his MMR vaccine and was diagnosed with viral encephalitis.
Basically [my son] went to the doctor's and he had his vaccination. My husband took him. He then came home, was quite agitated, was crying quite a lot, was fairly agitated, was a little bit unresponsive, couldn't be consoled.
So we gave [my son] the medication. It didn't, it sort of controlled his, his agitated state for a short while, but continued to be quite agitated over a couple of weeks. I had taken him back to the doctor's a couple of times because of, well, the way that he was. And they told me that he was, just had a viral infection that couldn't be treated. We approached Christmas, and on Christmas Day [my son] wasn't interested in his presents or any, I mean he was over a year old so he, you know, he did, kind of knew, but he wasn't terribly interested.
On Boxing Day we went in, and we were late waking him up, because [my son] hadn't woken us, and generally [my son] used to, up, you know, wake at half past six, seven o'clock. Half past nine, ten o'clock we wake up and think, 'Oh my Lord, [my son] hasn't woken up yet'. So we've gone into his bedroom and he was in the cot and he appeared as if he'd had a stroke. His face was all drooping on one side and he was dribbling a lot. We took [my son] up to our local hospital and basically sat in A & E for quite a while. But then referred up on to the children's ward. And [my son] continued, he was having episodes where he was just looking straight at us but didn't seem to be aware of what we were doing or even of what he was doing. Now this happened, had happened a number of times up until [my son] had gone to hospital, but I thought it was just, you know what some children are like, they're just like, 'I'm not talking to you. I'm not your friend. Go away, leave me alone'.
[My son] went into the hospital, was up on the children's ward. Basically sort of it got late in to the evening, he hadn't been seen, because there was only skeleton staff on with it obviously being Boxing Day. The, the doctor came in and saw [my son]. [My son] had an episode where he was very, he just flopped back on to the bed, very unresponsive. He was poking, 'Little [name], wake up' and all the rest of it. Called one of the members of staff. She came in, summoned the doctor straight away. And [my son] had actually had a major epileptic fit. But he hadn't had a seizure as such, he'd had an absent fit, which is petit mal epilepsy. They took him into a side room, put a line into his arm to give him intravenous antibiotics. Had a brain scan later that night and it turned out that he had encephalitis, which I believe to be triggered by the vaccine because it was one lead on from one to the other to the other. It was kind of a progressive state.
Describes the health problems her son continued to develop after viral encephalitis was diagnosed when he was thirteen months old.
Describes the health problems her son continued to develop after viral encephalitis was diagnosed when he was thirteen months old.
The doctors diagnosed [my son] with viral encephalitis at 13 months. When everything started that's what they said it was. We saw one doctor at our local hospital, who did tell us that she believed it was linked to the MMR vaccine. After he'd had the vaccination all his development stopped. He stopped babbling, virtually the day that he had the jab, because he was so distressed and progressively was distressed between that period and the Christmas period, he wasn't talking, he wasn't responsive, he wasn't like his, babbling his 'Mum, mum' and his 'Dad, dad'. That all stopped. And from that day to this [my son]'s never uttered another word.
Really?
Yes.
And he's now 8 years old?
He's 8 years old. He'll be 9 this year.
So he completely lost his speech?
Lost his speech. And became very uncooperative to say the least. He's now diagnosed with autism, epilepsy, possible Crohn's disease, he hasn't been investigated, that was due to me not taking him to the hospital. Because I thought he's got enough going on in his life with what he has, than to put him through something else. It doesn't really make any difference whether he has or he hasn't. He takes his anti-convulsants on his, a twice daily basis. He has to take laxatives on a daily basis. He takes Paracetamol like it's running out of fashion, just to try and keep him chilled. He's now on Diazepam to try and keep, and he's on an adult's dose, just to try and keep him level. But it's not, it's not really working.
One father talked about the changes that had occurred in his daughter 5 days after she had the MMR vaccine. She had episodic symptoms where she stammered, her eye movement changed, her language and speech regressed, she was reluctant to make eye contact, and she had a rash on her face.
A doctor at the hospital described it as post viral encephalitis. Over the next few days, she became detached and no longer wanted to play or dress up.
3 months after the MMR vaccine, more of her old self was coming back but she still had a stammer. He also said that, retrospectively, they had realised that there had been some mild changes in their son's behaviour at the time he had his MMR vaccine, but felt that in his son's case there was no evidence for a link.
One couple explained that 2 days after their 7-year-old son had his MMR vaccine when he was 13 months old, he developed a temperature, skin eruptions, a hacking cough and lost his appetite. After 2 weeks he continued to have little appetite, became socially withdrawn and started showing other symptoms of autism, and he was later diagnosed with onset regressive autism.
They also said that they had noticed some changes in their older son's behaviour when he was 13 months old. He was not diagnosed with autism, but he had 'a tendency to be literal about things' and to 'struggle sometimes in social situations and understand why other children do what they do'.
Describe the changes in their son from the time that he had the MMR vaccine.
Describe the changes in their son from the time that he had the MMR vaccine.
Mother: We have had the experience of seeing that our second son was damaged by the vaccines and without question, in our minds the trigger, the vaccine trigger for his autism, because that's what he has, regressive, late onset regressive autism. The trigger for that was the MMR vaccine. He was ill within two days of having the vaccine. I want to stress here, by the way that he wasn't suffering convulsions. You do hear of people who have very dramatic stories to tell and I'm not here to lie and say something happened that didn't happen. He wasn't convulsing. He wasn't fitting. But he wasn't well either. He ran a temperature and his skin erupted and he had a very, very, very worrying persistent hacking cough that just wouldn't leave him. Now that went on for two nights, and at the end of that I'd had enough and I took him back to the doctor. And that was the occasion when, eventually we got hold of his medical records and I couldn't believe because there in brackets was 'This child is not ill', underscored. And I thought well that's very odd.
Father: The point is as well
Mother: [our middle son], well if I can just finish the progression of what happened, so' he wasn't well. We noticed very quickly after that, that he wasn't eating properly. Now this is a child who'd eaten virtually everything we gave him, had a very good appetite and was actually quite forward because he was trying to feed himself. And even our unvaccinated baby hasn't quite got to that stage.
Father: [our middle son] was feeding himself at nine months, more or less.
Mother: Nine months, our second child was trying to spoon feed himself. That stopped and all, this child wanted was bottles, milk, milk, milk, want milk. We didn't worry initially because we thought well he's not been well. That's quite understandable that he's at the moment off his food. But the thing was he went off his food and stayed off his food. And from then on he never ate normally again. His diet became extremely restrictive, which is a very, very common feature of autism, very common indeed. And he would really hardly eat anything. But what he did want was milk by the gallon.
Within two weeks, we had noticed that he'd become very socially withdrawn and again that was a marked departure. This was a baby who had been extremely sociable and he had had very good eye contact. And responded when people walked into the room, he was looking to see where they were, very, very sociable baby. He, he was babbling. He'd got one or two words. Everything was there. Well, and the other noticeable thing was, how keen he was on his older brother, he'd sort of crawl after him and swarm all over him.
Well that stopped. And we started to notice that he was sort of removing himself and he'd be in a different part of the room and he'd have his back to everybody and he'd be sitting and looking at something. We noticed that within the fortnight, within a month we were starting to have worrying conversations with the nursery, he used to go to, suggesting the same thing. They were having real trouble giving him anything to eat and he was avoiding the other children. There were only young infants but he was avoiding them.
Father: It's documented in his books.
Mother: And he was never the same child again. Now that's something you often hear about autism is “Oh well, yes, but it, it sets in, in the second year of life”. And people link it, well I can’t answer for anybody else, but I do know that this set in within a very short space of time after him receiving the MMR vaccine. And I cannot believe that was a natural progression that just wallop happened at that time. I’m sure that vaccine triggered the onset of this autism, absolutely certain and you are as well, aren’t you?
Father: Hmhm, and again when we raised the, the point with the doctors concerned, they’re meant to raise a yellow card with a reaction to a vaccine because we went in and raised the point that he was not right since he’d had the vaccine. There was no yellow card registered and it seems to me and my wife, that reaction was sat on by the doctors.
Explains why they believe the changes in their son's behaviour were triggered by the MMR vaccine.
Explains why they believe the changes in their son's behaviour were triggered by the MMR vaccine.
Mother: And it was the timing of the whole thing, this became apparent, this change happened very, very quickly after him receiving that vaccine. Yes, I've had various doctors try to shoot me full of holes but I'm not talking about things that happened over six months after receiving this vaccine. These were symptoms that were really apparent or start, had started to become apparent within a fortnight. And since we'd made allowances for the fact that he'd been ill, if he hadn't been ill, we probably would have noticed it, perhaps even sooner.
But that was the point at which he changed and if' I always say when people question this and they're right to question it. But if you did a graph of his development and talking about his, you know, his social development and, and his development in terms of his motor development and everything else, it was steadily going up. In fact a lot of his milestones, he was meeting his milestones. I've had comments that I've listed from the health visitors, 'Bright social baby - six months old,' 'meeting his milestones well - eight months old', 'normal healthy little boy - one year old'. So this is a child that was developing normally and it's been witnessed and attested to and signed up to by health visitors and other professionals who apparently know what they are doing. He's been seen by different health visitors, as well. So this wasn't just one person, there were two or three different health visitors who saw him, all of whom documented that his development was normal.
Now it reaches an apex and then it goes down, and the turning point for that was, that happened in his thirteenth month. To me that is more than coincidental, other people will just have to make their own minds up. And I do realise that there are some people who will say, 'This is coincidence', and 'poor sad parents, they're looking for a peg to hang this on'. But that was our experience and that's why we make that link, it was too coincidental. This isn't something blithely second year of life. Second year of life is a twelve month period. This happened or it started to happened and symptoms were apparent within a very, very small time frame, that's how we make the link.
None of the people we spoke with had a child who had a severe reaction to an MMR vaccine.
*A serious allergic reaction (less than one in a million doses); this would occur within a few hours of the immunisation, and the signs would be wheezing or difficulty with breathing, a rash (like a nettle sting), paleness, being floppy, and/or a fast heartbeat. Seek medical advice immediately.
See also 'Mild or intermediate reactions to the MMR vaccine'.
Last reviewed: April 2025.
Last updated: April 2025.
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