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Welcome to Public Health

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on Call, a podcast from

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Question at JHU.EDU. That's Public

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Health Question at JHU.EDU.

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for future podcast episodes.

0:29

Hey listeners, it's Lindsay Smith

0:32

Rogers. They're back. Questions

0:34

about whether vaccines are linked

0:36

to autism. Professor Daniel Solomon

0:39

is the director of the

0:41

Johns Hopkins Center for Vaccine

0:43

Safety. He joins Dr. Josh

0:45

Sharstein to talk about where

0:47

this concern started, why experts

0:49

have concluded there is no connection,

0:52

and why nonetheless questions

0:54

persist. Let's listen. Professor

0:57

Dan Salmon, thank you so much

0:59

for joining me today in public

1:01

health on call. How are you doing?

1:03

I'm doing well, Dr. Sharfstein.

1:06

Thank you for inviting me. So

1:08

I want to reintroduce you to

1:10

our audience. You run the Institute

1:12

for Vaccine Safety at Johns

1:14

Hopkins. That's correct. Would it be

1:16

fair to say that your career has

1:18

been devoted to understanding safety

1:21

risks of vaccines and working

1:23

to make vaccines safer? That's

1:25

right. You know, I've also done

1:28

a lot of work looking at

1:30

why people get vaccines and their

1:32

decision-making, but a lot of my

1:34

work is focused on vaccine safety

1:36

science and improving that science. Why?

1:38

Why did you pick that topic? Well,

1:40

it probably found me more than I

1:42

found it. My work in this space started

1:45

when I was a student at Emory,

1:47

and an article came out in

1:49

the Atlanta Journal about a

1:51

chiropractor telling his patients not

1:53

to vaccinate. and that caught

1:56

the attention of David Sandcher,

1:58

the CDC director. And I

2:00

had initially been working at

2:02

HIV and was brought in

2:04

to look at the risks

2:06

of unvaccinated children, which naturally

2:08

led to vaccine safety. So

2:10

let me ask you roughly

2:12

what year was that? That

2:14

was more than 30 years

2:16

ago. So you've been in

2:18

and around questions of vaccine

2:20

safety for more than 30 years.

2:23

That's correct. All right, so

2:25

I want to ask you

2:27

about something. that has been around

2:29

maybe for just as long,

2:31

which is concerns about vaccines and

2:34

autism as a side effect

2:36

of vaccines. Can you tell me

2:38

when this question popped onto

2:40

your radar screen? Well, the issue

2:43

was first raised by an

2:45

article published by Andrew Wakefield.

2:47

He was a GI doc in

2:49

England Royal Free Hospital, very

2:51

well-known hospital, and he had published

2:53

a paper in the Lancet.

2:55

which as you know is a

2:58

very good journal, and he

3:00

looked at 12 children, most

3:02

of whom the parents reported developing

3:04

autism after getting the vaccine.

3:06

And that's really when the MMR

3:09

issue and autism arose. So

3:11

before that, it wasn't really a

3:13

common topic to talk about

3:15

vaccines and autism, but after that

3:17

article appeared in the Lancet

3:19

in the Lancet, suddenly it

3:21

received a lot of attention. Prior

3:24

to that I don't think

3:26

anybody really talked about vaccines and

3:28

autism and after that there

3:30

was a tremendous amount of discussion

3:33

in that space. And research.

3:35

And research. You know I

3:37

think that initial research and public

3:39

health response to that study

3:41

was fairly limited because it was

3:44

only 12 children and it

3:46

was described as a case series

3:48

although really it wasn't even

3:50

a case series because typically a

3:52

case series would be consecutive

3:54

children. and these weren't consecutive

3:56

children but it was described as

3:59

a case series and uh...

4:01

you know a case series can't

4:03

really tell you about something

4:05

causing something. It can perhaps raise

4:08

the question but not answer

4:10

the question. But once that paper

4:12

was published in the press

4:14

release and moving forward, the

4:16

lead author, Dr. Andrew Wakefield, you

4:19

know, went around telling a

4:21

lot of people that he had

4:23

shown vaccines had caused autism,

4:25

which that study couldn't even do.

4:27

I mean, it's... A bit

4:29

of a stretch even calling

4:31

it a study. It's a description

4:34

of 12 children. There was

4:36

no control group or control period.

4:38

It was simply a description.

4:40

And maybe now's a good time

4:43

just to point out what

4:45

wound up happening to that study,

4:47

the study that really sparked

4:49

the whole discussion of vaccines

4:51

and autism. Well, it got retracted

4:54

ultimately. Within a short amount

4:56

of time, several of the authors

4:58

pulled their names. There were

5:00

lots of problems later found with

5:02

what was published, including, as

5:04

I mentioned, they weren't consecutive

5:06

children. They were just cherry-picked children.

5:09

And, you know, we know

5:11

that given when vaccines are given,

5:13

and when children regress into

5:15

autism, that there will be a

5:18

temporal relationship. It'll happen by

5:20

chance alone. So, you know, from

5:22

a scientific perspective, it didn't

5:24

show much. But you had

5:26

a very well-credentialed, very charismatic person

5:28

coming from an outstanding institution

5:30

publishing this paper in a very

5:33

prestigious journal and he really

5:35

ran with it. I remember at

5:37

the time I had a

5:39

young child and I got

5:41

a call from my mom and

5:44

my mom is a very...

5:46

intelligent, well-educated woman. She had a

5:48

PhD in community development and

5:50

she called and said, you know,

5:53

I saw this guy on

5:55

60 Minutes and I know this

5:57

is what you do because

5:59

the time I was working

6:01

in the CDC's vaccine safety group,

6:03

as she said, so I

6:05

don't mean to tell you, like,

6:08

I know more than you,

6:10

but, you know, watching him on

6:12

60 minutes made me really

6:14

nervous. And maybe you should

6:16

think about separating those MMR antigents

6:19

and giving separate shots, because

6:21

that's one of the things that

6:23

he was proposing. And it

6:25

was remarkable to me that even

6:28

with someone who was very

6:30

well educated, and a very public

6:32

health-focused person, she found him

6:34

very compelling. And let me

6:36

ask you, Dr. Sharfstein, as I

6:38

remember, you've met him, you've

6:40

spoken with him. So what were

6:43

your impressions of Dr. Wakefield?

6:45

You're right. I did have a

6:47

chance to meet Dr. Wakefield.

6:49

It was when I was

6:51

working on Capitol Hill. It was

6:54

some time after his initial

6:56

paper was published, and I did

6:58

find him quite charming and

7:00

engaging. even though I didn't agree

7:02

with what he was saying,

7:05

I appreciated why so many people

7:07

were listening to him and

7:09

why what he had done

7:11

had generated an enormous amount of

7:13

attention. I wonder whether it

7:15

was just Dr. Wakefield that turned

7:18

the question of vaccines and

7:20

autism into a topic people really

7:22

wanted to address or were

7:24

there other factors too? Well, I

7:27

think that autism is characteristic

7:29

of a lot of health

7:31

outcomes that are just right for

7:33

vaccine safety controversies. They happen

7:35

or at least they become apparent

7:37

to the parent early in

7:39

childhood around when we give a

7:42

lot of vaccines. It seems

7:44

to be increasing in incidents

7:46

or prevalence. So there's more of

7:48

it out there. And we

7:50

don't understand or fully understand the

7:53

ideology. We don't know what

7:55

causes it. So you have a

7:57

lot of parents that are

7:59

watching their children developed normally. and

8:02

then regress into autism and

8:04

they want to know why.

8:06

They want to know what happened.

8:08

And in addition... you had

8:10

advocacy groups, autism advocacy groups, where

8:12

these parents came together looking

8:14

for answers and looking for support

8:17

for their children. So as

8:19

you think about an issue

8:21

like this, you have parents going,

8:23

wow, what happened? What did

8:25

I do? What happened to my

8:28

child to cause this outcome,

8:30

this autism? And then they go,

8:32

wow, he or she had

8:34

just gotten vaccinated. And then they

8:37

talk with other parents of

8:39

autistic children, and they start

8:41

to go, wow, my child just

8:43

got vaccinated too. And, you

8:45

know, parents are looking for answers,

8:47

understandably, and they land upon

8:49

vaccines. And so the issue was

8:52

very ripe for it to

8:54

be associated with vaccines, not

8:56

by cause and effect, but by

8:58

timing and temporality. Let me

9:00

ask you about the research that

9:03

was spawned by this controversy

9:05

because there was a lot of

9:07

interest in addressing the question

9:09

that was on people's minds. Well,

9:11

whereas I said you can't

9:13

draw conclusions from looking at

9:16

a dozen kids, you need to

9:18

have controls. And so this

9:20

issue and the attention it got

9:22

and the concern of parents

9:24

led to a number of large...

9:27

epidemiological studies where they looked

9:29

at kids who were vaccinated

9:31

and weren't vaccinated in this case

9:33

with the MMR vaccine so

9:35

you had control groups and those

9:38

studies found no association between

9:40

MMR vaccine and autism. And there

9:42

were studies done on other

9:44

vaccines as well? There were. Well,

9:46

once it started to become

9:48

clear that MMR vaccine was

9:50

not associated with autism and during

9:53

this time some of the

9:55

conflict that Dr. Wakefield had started

9:57

to become a parent, the

9:59

hypothesis shifted from MMRA vaccine to

10:02

Thamericol and Vaccine. At the

10:04

time, Thamericol was used as

10:06

a preservative in some childhood vaccines.

10:08

And parents said, oh, okay,

10:10

it's not MMRA vaccine. It's Thamericol.

10:13

Thamericol, which was never in

10:15

the MMRA vaccine because it's a

10:17

live vaccine. It was used

10:19

as a preservative in multi-dose files.

10:21

And that led to a

10:23

number of studies looking at

10:25

the Marisol in vaccines and autism.

10:28

And those studies also found

10:30

no relationship. And, you know, it's

10:32

a bit of a wackamole

10:34

because once the Themarisol hypothesis had

10:37

been answered by a number

10:39

of large studies, the hypothesis

10:41

shifted again. Oh, it's not MR

10:43

vaccine. It's not the Marisol

10:45

in vaccines. It's the number of

10:48

vaccines you give at one

10:50

time. And then there were studies

10:52

of that and also found

10:54

no relationship between vaccines and autism.

10:56

So at this point we

10:58

have 16 well-conducted studies, large

11:00

population-based studies carefully designed, done by

11:03

different investigators in different countries

11:05

using different but strong methods, and

11:07

all 16 of them found

11:09

no relationship between MMRA vaccine. the

11:12

marathon vaccines, the number of

11:14

vaccines given in autism. So the

11:16

evidence is really quite compelling.

11:18

So that brings us to

11:20

the present moment, because despite all

11:22

of this research, we have

11:24

not just the Secretary of Health

11:27

and Human Services, but also

11:29

the President of the United States

11:31

saying that there should be

11:33

more research and the latest

11:35

headlines indicating that there might be

11:38

more research into this same

11:40

question. The first thing I want

11:42

to ask you is... Why

11:44

do you think this theory has

11:47

persisted despite? So much research

11:49

and conclusions about it that have

11:51

been made you know over

11:53

the years Well, I think

11:55

it's a complicated question if there's

11:57

not a single simple answer

11:59

to that I'm not an autism

12:02

researcher But my understanding is

12:04

that we've identified some causes for

12:06

autism and it really should

12:08

be autism's because there's probably

12:10

multiple diseases and multiple causes But

12:13

there's still a lot of

12:15

causes we haven't identified So the

12:17

question of what causes my

12:19

child's autism or autism spectrum disorder

12:22

is still out there. That's

12:24

one part. Another part is that,

12:26

you know, it took a

12:28

bit of time for those

12:30

studies to be done. More than

12:32

a year for the first

12:34

study after the MMR vaccine hypothesis

12:37

and in the case of

12:39

Themarisol years. And, you know, that's

12:41

not a long time, but

12:43

when you have somebody... charismatic,

12:45

well-credentialed person traveling the world and

12:48

advocacy groups and parents jumping

12:50

on the issue, it creates a

12:52

void, it creates an opportunity,

12:54

a vacuum of information. And you

12:57

know it's much easier for

12:59

information and science to inform someone's

13:01

views than it is to

13:03

change their mind. And, you

13:05

know, at this point in time,

13:07

about a quarter of the

13:09

parents thought that vaccines cause autism.

13:12

They had already made up

13:14

their mind. And it's very hard

13:16

to change somebody's mind. I

13:18

mean, you have heuristics like

13:20

cognitive dissonance, and I think if

13:23

the science had been done

13:25

sooner, and understanding, it's hard to

13:27

do good science. It's easy

13:29

to do bad science, but it

13:31

takes time and efforts to

13:33

do good science. But I think

13:36

if the science were done

13:38

sooner, that would help. I

13:40

think there was also often... distrust

13:42

of those who were doing

13:44

the science. And we see that

13:47

now. When people don't like

13:49

the message, they attack the messenger.

13:51

And I think if we

13:53

had had more trust in

13:55

public health authorities and more trust

13:58

in those doing the science,

14:00

it may have been received in

14:02

a more impactful way. What

14:04

do you think about the idea

14:06

of doing more research on

14:08

whether vaccines are linked to autism?

14:11

Well, you know, as we've

14:13

talked about before, Josh, I'm

14:15

a scientist and I believe in

14:17

the value of science and

14:19

I think there's lots of places

14:22

in vaccines and vaccine safety

14:24

where we can and should do

14:26

more science. There's a lot

14:28

we know. And there's a

14:30

lot of science being done and

14:33

the science that has been

14:35

done has shown that vaccines are

14:37

very safe. They're not perfectly

14:39

safe. They do sometimes very rarely

14:41

cause adverse reactions, but overall

14:43

they're very safe. But there are

14:46

places we can and should

14:48

do more science. When it

14:50

comes to autism, I feel like

14:52

the science has already been

14:54

done. It's very compelling. So if

14:57

you gave me a pot

14:59

of money... and said, let's do

15:01

more vaccine safety research, which

15:03

would be great. Autism would not

15:06

be high up on my

15:08

list because the science is

15:10

already quite compelling. Do you have

15:12

any concerns, as you said,

15:14

that doing good science is hard,

15:16

do any concerns that the

15:18

kind of research that might be

15:21

done might not be well

15:23

designed? I do, because, you

15:25

know, good science can inform people's

15:27

decisions. and policy and practice,

15:29

but bad science can be very

15:32

hurtful because they can confuse

15:34

people and you can't rely on

15:36

the results. But as you

15:38

mentioned earlier in your experience with

15:40

Dr. Wakefield, you as somebody

15:42

with training in medicine and

15:44

public health were able to listen

15:47

to and decipher the arguments

15:49

being made. But that's not a

15:51

skill set the average parent.

15:53

or the public has. So I

15:56

think bad science could be

15:58

quite harmful. Just to be

16:00

clear, when you say good science

16:02

versus bad science, you're not

16:04

talking about what the study finds.

16:07

You're talking about how the

16:09

study is actually designed to answer

16:11

the question. Yes, I'm talking

16:13

about the rigor of the methods.

16:15

Could you give maybe one

16:17

final example of a rigorous

16:19

study versus a not rigorous study?

16:22

Well, so study, you know,

16:24

it seems like this should be

16:26

easy. It seems like, oh,

16:28

well, we should just compare vaccinated

16:31

to unvaccinated children. And one

16:33

of the things that we

16:35

often hear from people worried about

16:37

vaccines is we need to

16:39

do a vaccinated, unvaccinated study. And

16:42

intuitively, that makes a lot

16:44

of sense. If you want to

16:46

know if smoking causes lung

16:48

cancer, you look at the rates

16:50

of lung cancer among smokers

16:52

and non-smokers. You know, it's

16:54

rather straightforward, but in fact, it's

16:57

more complicated than that. Because

16:59

using the smoking example in lung

17:01

cancer, If you looked at

17:03

the rates of lung cancer among

17:06

drinkers, you would find it's

17:08

actually higher than non-drinkers. And

17:10

somebody might conclude, oh, well, drinking

17:12

causes lung cancer. Well, that's

17:14

not the case. The issue is

17:17

that people that drink are

17:19

more likely to smoke. And smoking

17:21

causes lung cancer. So drinking

17:23

would be a confounder. Drinking would

17:25

be something that's associated with

17:27

the exposure and the outcome,

17:29

but not a part of the

17:32

causal pathway. And in the

17:34

case of looking at vaccinated versus

17:36

unvaccinated children, if you look

17:38

at children that are truly unvaccinated,

17:41

you know, it's about 2%

17:43

of American children. And that

17:45

2% is very, very different than

17:47

the 98%. So for example,

17:49

I've received an email last week

17:51

that said, why can't you

17:53

just look at Amish children? And

17:56

we can figure out whether

17:58

or not vaccines cause autism and

18:00

other health outcomes. Well, Amish

18:02

children are very very different.

18:04

than other children. And you can,

18:07

I mean, I don't know

18:09

what you would find regarding autism,

18:11

but they're different in their

18:13

lifestyle, they're different in all sorts

18:16

of environmental exposures and what

18:18

they eat, and importantly, they're very

18:20

different in terms of how

18:22

they access and use medicine

18:24

and health care. And my guess

18:26

is, and I've never studied.

18:28

autism among Amish children, but even

18:31

if the rates were about

18:33

the same, they're probably much less

18:35

likely to get diagnosed. So

18:37

this study is very complicated,

18:39

and I brought up the issue

18:42

of confounding, and you really

18:44

have to adjust confounding when you

18:46

look at vaccine safety studies,

18:48

and you really have to look

18:51

at health care utilization. And

18:53

so these studies can be done.

18:55

They've been done. They're just

18:57

not easy to do. And

18:59

sometimes it's not intuitive. Thank you

19:01

so much for coming to

19:03

the podcast, talking about this issue,

19:06

which remains in the news

19:08

and shedding a lot of light

19:10

on what caused the controversy

19:12

and where we are today.

19:14

It's a pleasure. Thank you, Dr.

19:17

Sharfstein. Public Health on Call

19:19

is a podcast from the Johns

19:21

Hopkins Bloomberg School of Public

19:23

Health, produced by Joshua Sharfstein, Lindsay

19:25

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