Vaccines and the autism myth – part 1 | Infectious diseases | Health & Medicine | Khan Academy

February 16, 2020

So for the last
20, 30 years, we’ve noticed this increase in autism. I’m actually going
to quickly sketch out a graph to show you what I mean. We have autism rates over here. And if you follow them over
time, basically what happens is that you see that
things are going upwards. And the main reason that
people cite is awareness. They say, well, if more
parents and families are aware of autism because we
talk about it more nowadays, then of course, they’re going to
bring it up with their doctors and it’s going to get diagnosed. And although that may be
one reason for the increase, people have been searching
for other reasons to explain the increase as well. Now in 1998, there was a team
of doctors and researchers that put together a
study, a study that we call the Wakefield Study. It’s named after the
main author, which was a guy named Dr. Wakefield. He was a surgeon
working in England. And, in total there
were 13 people, 13 authors on this study. So this study was done in
the United Kingdom, the UK. And what they did is
they took 12 children, and these children came into
the hospital, reportedly the normal way, the
routine way that children come into the hospital. They weren’t recruited. And he found that they had
developmental problems. So these are 12
children with some sort of developmental
problem or delay, and the most common example
of a developmental problem among these kids was autism. So a lot of these kids ended up
having a diagnosis of autism. And what they did– I’m actually
going to sketch out for you. So let’s imagine that
this is the head of one of our children. What he asked them was,
do they have any symptoms? When did their symptoms start? All of these kinds
of things to get at their history,
their medical history. And a lot of the families
said, well, you know, we remember them having
these symptoms of autism, which I’m drawing as
a grayed-out brain, and there seems to be– this
is the parents talking now. They felt like there was
some sort of relationship with the vaccine. They felt like they remembered
the vaccine, specifically the MMR vaccine, the measles,
mumps, rubella vaccine, around the time
that symptoms began, and that’s what he reported. So we actually have
now a relationship based in terms of
parents’ recollection between the vaccine and autism. But what this study was mainly
about was actually the gut. So he was a surgeon
and he wanted to look at the
intestines of these kids and he noticed that on
the intestinal biopsies– when you actually got
a little bit of tissue from these intestines– a
lot of them had inflammation. That was what his paper
was primarily about, was this inflammation
that he saw. So he proposed– and
this is a big deal. He proposed that vaccine was
causing this inflammation. He thought that was the
cause of the inflammation, and he then thought
that perhaps there was some mystery protein– let’s
say this blue little protein– that maybe you take
in through your diet, that now, because it’s
inflamed, can get across the gut and can affect the
developing brain. So this was how
he proposed there could be a link between
the vaccine and autism. Now when the Wakefield Study
first came out in 1998, you can imagine the
kind of excitement this created for a lot
of parents and families that had been for years looking
for something to explain why their kid had autism. And so, finally, people could
circle this and say, ah, maybe it was the vaccine
that caused autism, and that’s what people thought. But there were a couple of
problems with this idea. The first problem was that
some of the patients that had autism symptoms,
they actually reported that they were having
these symptoms before they had any of the gut symptoms. Now think about that. If you’re having autism symptoms
before gut symptoms, not after, then that really goes
against this theory, because this theory is
based around the idea that it’s the gut
that comes first. So immediately, this is one
concern and a big question mark over here whether
this is really true. Another question mark is
around this mystery protein. I’ll put it up here. So this mystery protein–
this is something that Wakefield never
really identified. He never said, well, I think
it’s this protein or that one. And in the last 15
plus years, nobody’s found any mystery
proteins that would explain what Wakefield
was suggesting. So the fact that nobody can
actually find these proteins is also another
big question-mark. Nevertheless, a lot of
studies started getting done. People started saying,
well, if there truly is a relationship between
vaccines and autism, then let’s explore that further. So a group of studies were
done around MMR vaccine rates. How often in a population
do you actually see people getting
the MMR vaccine? And you’d imagine
that if there truly is a link between
vaccine causing autism– if that’s true, then, of
course, the vaccine rates must be going up. That would explain
the autism going up. And so they actually looked
in a few different places, and, of course, the first
place to talk about it is the UK, because, of course,
this study was initially done in the UK. And in the UK, they
looked over six years, and they found that,
actually, MMR vaccine rates had been steady. There had not been an increase. So already this
is a little weird if we’re thinking that the
vaccine is causing autism. You’d expect
something different. So they looked again. They actually
looked another time. This time they actually
looked in the US. And in the United States they
did this study over 15 years. And over 15 years,
the same thing, steady vaccine rates even though
autism rates were going up. Now another study
was actually done, this time in Canada
and, surprisingly, in Canada it turns out that
the vaccine rates were actually going down slightly. So vaccine rates
over 12 years now went down, even though
autism rates were going up. So this data is done at
the population level, but it really does
go against this idea that vaccine is causing autism. But people weren’t
satisfied with that. They wanted more
specific research to be done on this mechanism
that Dr. Wakefield proposed. So another study was done. It actually was done
in the United Kingdom, and this study looked at
473 autistic children. So remember, the initial
study was done on 12 children, and now we’re
looking at hundreds of children with autism,
and among these 473, they actually wanted to
figure out this part of it. They said, is there a
link between vaccine and any sort of gut
inflammation and the answer was a resounding no. There doesn’t seem to be any
relationship in autistic kids with vaccine, MMR vaccine
and inflammation of the gut. So that was actually very
detrimental to Wakefield’s theory. But what about the second part,
the second link between gut inflammation and any sort of
autism, this part right here? Well, again, another study
in the UK looking this time at 262 autistic children
found that there was no link between
these two things. So gut inflammation
and autism did not seem to be related at all. So now the two important
components of Wakefield’s idea didn’t seem to bear out. And then I should also
just cross this off, this mystery protein bit,
because, again, people have been looking for that,
and no one seemed to find that. But that wasn’t good enough
because you could say, well, maybe there still is some link
between vaccine and autism, but maybe this mechanism
wasn’t quite right. So research got done on
this purple arrow over here. So they said, OK,
what about this? Could it be possible that
there’s a link between the two using some other mechanism. And so a study was
done in the UK, specifically looking at
MMR vaccine and autism. Is there a relationship? And it turns out that
they, in this study, looked at 71 autistic
children, and they found that among these children
there was no relationship. And this study was actually
in a way done again. In fact, in another setting
done in a different way, but also trying to
answer the same question of a link between vaccine and
autism in Finland this time. They found that among
309 autistic children, there was no link. Now, remember this
link that we created was done among 12
children and now we have hundreds and hundreds of
kids in different countries. Another one was done in the US. And all these studies are
finding the same result, that basically
there were no links that they could find
between vaccine and autism. And so people started
really doubting the truth behind that very first
study, that first study done on 12 kids. But people were still
talking about it and said, you know, what about
that Wakefield Study? Isn’t it possible
that there could still be a link in spite of
all this other evidence? So, finally, a
group out of Finland tried to do another type of
study, a different approach, that they thought
would conclusively answer the question. They basically said, well fine. Why don’t we follow
1.8 million children. So obviously this is
many, many children that are getting vaccinated
and just follow them over time and see if they develop autism,
and this might answer once and for all whether
there’s a link. And so they followed
these kids over time, and they found a grand
total of zero cases of vaccine-associated autism. So in all these cases of
vaccination, none of them resulted in autism. So at this point,
people really stopped believing the study,
the Wakefield Study, and whether there was any link. That was kind of resolved. All of these studies
said, no, there was really no link between
vaccine and autism, but a question remained
around the Wakefield Study and how those results were
found in the first place. I’m actually going
to pause right there and we’ll jump into
that in the next video.

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