Файл: Medical_Myths_Lies_and_Half-Truths_guidebook.pdf

38

Lecture 10: V

accination Bene

¿

 ts—How W

ell V

accines W

o

rk

The next type of vaccine is the inactivated vaccine. Here you take a virus or 
bacteria and essentially kill it. You inactivate it so that it cannot reproduce, 
but it still has all the proteins on the outside. There is a small risk of 
infection with an inactivated 
vaccine—but only if the virus 
is improperly inactivated. 
With proper inactivation, 
there is zero risk of infection. 
Inactivated vaccines may not 
be quite as effective as a live 
vaccine. For this reason, they 
are more likely to require 
booster shots. 

Then there are subunit 
vaccines. These contain not 
even an entire virus—just 
part of the protein shell, for 
example. Here, there is no 
risk of infection. Conjugate 
vaccines combine a toxin or 
an immunogenic protein to 
the coat, because certain coats 
are not very immunogenic. But, if you couple it with something else—a 
toxin or something that’s really good at stimulating the immune system—the 
immune system will be activated against it. 

Toxoid vaccines are vaccines not against the organism of a virus or bacteria, 
but against a toxin that the virus produces. Toxoid vaccines do not prevent 
an infection, but the antibodies will bind and inactivate the toxin as it’s being 
released. Therefore, it will prevent the negative health consequences of the 
infection while allowing the infection to run its normal course. 

Do vaccines work? There are still today people who question whether 
vaccines work. But the evidence is extremely clear: Vaccines are about 
95% effective. This means that 95% of people who are vaccinated with 
a vaccination schedule—which may involve boosters—will develop a 

Modern vaccines are about 95% effective. 

© iStockphoto/Thinkstock.

39

functional immunity to the substance against which they’re being vaccinated. 
Vaccines are less effective in elderly and immunocompromised people. That 
is a serious concern because those are often the very people that we need to 
protect the most. 

This leads us to the concept of herd immunity. There are estimates that 
when about 90% or more of any population—people who are likely to be 
exposed to each other—are vaccinated against an infection, you achieve herd 
immunity. That infection cannot easily spread from person to person. Anyone 
who is harboring the virus or bacteria is very unlikely to encounter somebody 
else who isn’t immune. Therefore, they’ll be able to 

¿

 ght it off before they 

spread it around. This prevents outbreaks and also prevents infections from 
being endemic. 

Ŷ

Allen, 

Vaccine

. 

Henderson, 

Smallpox.

1. 

How do vaccines work?

2. 

How much evidence is there for the safety and effectiveness 
of vaccines?

    Suggested Reading

    Questions to Consider

40

Lecture 1

1: V

accination Risks—Real and Imagined

Vaccination Risks—Real and Imagined 

Lecture 11

Rumors began to spread that squalene in the vaccines given to Gulf 
War veterans was linked to Gulf War Syndrome. The gaping hole in 
this hypothesis, however, is that squalene was never even in the vaccines 
that those soldiers were given. 

C

ontinuing our discussion of vaccines, I’m going to turn now to talking 
about some myths about fears and about the safety of vaccines. We 
begin with a well-known myth about autism. A UK physician named 

Andrew Wake

¿

 eld published a 1998 paper in 

The Lancet

 that claimed that 

he found a correlation between autism, which is a neurodevelopmental 
disorder; gastrointestinal disorders; and infection with the measles virus. The 
paper did not directly implicate vaccines. However, in the subsequent press 
conferences and media contacts that Wake

¿

 eld had, he speci

¿

 cally spread 

concerns about the MMR (mumps, measles, and rubella) vaccine being 
linked to this gastrointestinal-autism disorder connection. MMR fears spread 
from that point for the following decade and beyond. 

In the UK, vaccination rates with the MMR vaccine dropped from about 92% 
in 1996 down to as low as 84% in 2002. In some parts of London, compliance 
rates were as low as 61% in 2003. That’s a dramatic decrease in the number 
of people willing to take the MMR vaccine or give it to their children. 
These rates are low enough that they’re below herd immunity. That’s that 
magic number of people who are vaccinated—around 90%—that prevents 
the endemic spread of an infection. This subsequently led to outbreaks of 
diseases that had been previously removed as endemic in the UK, such as 
measles. A similar thing happened shortly after that in the United States: 
The rates dropped, particularly in certain populations, and those populations 
became susceptible to previously eliminated diseases. 

Wake

¿

 eld was later found to have undisclosed con

À

 icts of interest. He was 

actually applying for a patent for a replacement measles vaccine. He was also 
being funded by lawyers who were engaged in lawsuits on behalf of parents 
who were claiming that their children’s autism was caused by the MMR 

41

vaccine. Even later, there were allegations made that the data in his original 

Lancet

 paper, or some of that data, may have been faked. This is because it 

didn’t square with hospital 
records that were then re-
reviewed. In 2010, based on 
these undisclosed con

À

 icts 

of interest and these 
allegations, 

The Lancet

actually withdrew his paper 
from the published record. 
Wake

¿

 eld was found guilty 

of professional misconduct 
in the UK and no longer 
has a license to practice 
medicine there. However, 
the damage had already 
been done. Fears about a 
correlation between the 
MMR vaccine and autism 
were already spreading.

A 2010 survey found that as 
many as 25% of U.S. parents 
think there is a link between 
vaccines and autism. In that same survey, 9 in 10 parents think that vaccines 
are important to the health of their children. This indicates that there’s a 
certain amount of confusion in the general population about the safety 
of vaccines.

Ultimately the question of the safety of vaccines is not about the ethics or 
the research of one scientist; it’s about the scienti

¿

 c evidence. There have 

been a number of studies on whether there really is a connection between the 
MMR vaccine and autism or other neurodevelopmental disorders. Data from 
Poland, the UK, Denmark, Finland, and Japan all independently found that 
there is no connection whatsoever between MMR and autism. 

Independent studies in several countries 
found no connection between the MMR 
vaccine and autism. 

© iStockphoto/Thinkstock.

42

Lecture 1

1: V

accination Risks—Real and Imagined

In the years following Wake

¿

 eld, when research was progressively clearing 

MMR vaccine as a correlation with autism, those who were having fears 
about the MMR vaccine shifted to fears about thimerosal. Thimerosal is in 
some vaccines, but was never in the MMR vaccine. It is a mercury-based 
preservative added mainly to multidose vials or some inactivated vaccines 

to prevent bacterial contamination. 
It has been used for decades in 
many health and beauty products, 
not just vaccines.

The question is whether the 
ethylmercury in thimerosal is 
toxic to people—and speci

¿

 cally 

to children—in the doses that you 

get from the vaccines. Mercury certainly is a neurotoxin; nobody denies 
that. The toxicology of mercury is pretty clear. However, autism does not 
resemble mercury toxicity. They’re both neurological disorders, but the 
details of the signs and symptoms are different enough that we can say 
they’re distinct disorders. 

Over the last decade, there have been multiple studies in multiple countries 
looking at any correlation between exposure to thimerosal and the risk of 
developing either autism speci

¿

 cally or neurodevelopmental disorders 

in general. These studies have shown no correlation. Most signi

¿

 cantly, 

in the United States the government decided to remove thimerosal almost 
completely from the routine childhood vaccine schedule. This removal was 
completed certainly by the beginning of 2002. The result of this was that 
the cumulative dose that children were exposed to from the entire vaccine 
schedule has been dramatically decreased. Those who were most vociferous 
about a connection between thimerosal and autism predicted that autism rates 
would plummet after the removal of thimerosal from the vaccine program. 
This did not happen. In fact, the autism rates continue to increase at exactly 
the same rate. 

There are other vaccine myths that have cropped up as well. One myth is that 
we don’t need to vaccinate against diseases that are no longer endemic. But 
the only time we can really safely stop using a vaccine is when a disease is 

I think of all the myths that I 
cover in this course, myths 
surrounding vaccines have the 
potential to do the most harm.