-Aluminum, formaldehyde, dead viruses --
Why would we put any of those things in our children's bodies?
This is a legitimate question
that many parents ask about vaccines.
So, what's actually in them, how are they made,
and are the ingredients harmful?
In the last episode, we learned how the smallpox vaccine
was made over 200 years ago.
It was super effective
and ended up eradicating smallpox all over the globe.
But the way it was produced,
by taking pus from one person or animal
and giving it to another,
was really crude compared to the vaccines that came after it.
I mean, ew.
But the technology got way more advanced.
Take diphtheria.
It's a disease most people in developed nations have never
seen because of successful vaccination programs.
But through the 1800s, it terrified American families.
Diane Wendt from the Smithsonian's National Museum
of American History told me about it.
-diphtheria's an infectious disease
that's caused by a bacteria.
It was called "the scourge of childhood"
or even "the grim scourge of childhood,"
and "the strangling angel" was another name for the disease.
And part of what was really scary about the disease is that
the bacteria that gathers and starts in the throat
and everything produces a toxin.
So, it's poisoning the body,
but it also kind of kills off cells,
and it produces this membrane,
which they called a pseudomembrane,
which can actually close off the throat
and, basically, asphyxiate a young child.
diphtheria could be lethal, and there was no way to cure it,
though doctors had some fairly gruesome ways
to help children breathe.
One was to perform a tracheotomy
by making a hole in their throat.
Another was to insert a breathing tube
through the pseudomembrane.
-You can see 1, 2, and then we get 6, 7,
8, 9, and 10 to 12.
And that's actually the ages of the kids
that it was intended for.
-That's so heartbreaking.
But things changed dramatically in the 1890s
with a new type of treatment.
-Unlike smallpox, which the treatment and the vaccine
for smallpox kind of arose
out of an empirical almost folk medicine,
if you will, this was a treatment
that really came out of what was scientific medicine
in the new science of bacteriology.
-The treatment was called "antitoxin,"
and, essentially, it was a preparation of antibodies
that neutralized the diphtheria toxin.
It was made by injecting horses with the toxin,
waiting for them to build an immune response,
harvesting antibodies from their blood,
and giving those antibodies to diphtheria patients.
Now, I don't want to minimize the effect
the bleeding had on the horses, but know that horses
are less affected by diphtheria toxin than humans are,
so they only developed a low-grade fever.
-The new treatment came out of the bacteriology lab in Germany,
and it was kind of announced to most of the world in 1894,
and there was so much demand for it
and so much excitement over it, that, in the United States,
the public health departments immediately
put things into force to try
and start to make this new treatment.
-Now, antitoxin was a treatment, but not a vaccine.
It didn't confer long-term immunity
because the patient's own body
wasn't learning how to make antibodies,
but, eventually, scientists figured out
how to create an inactivated form of the toxin
called a "toxoid."
Toxoids could evoke an immune response in a healthy person
without making them sick, so if the person
ever encountered diphtheria in the future,
their immune system would know which antibodies to produce.
This is how most vaccines today are made.
We use toxoids or weak or dead version of germs
to bring on an immune response.
For example, diphtheria and tetanus vaccines
still use toxoids.
The measles vaccine uses a highly weakened form
of the measles virus,
and the polio vaccine uses a dead virus.
Now, here's the thing.
Toxoids are so harmless that your body
sometimes doesn't bother mounting an immune response.
This was initially the case with the diphtheria toxoid.
It just didn't make the immune system angry enough.
But back in the days of the antitoxin treatment,
scientists found that when horses had
a little inflammation at their injection sites,
they actually produced more antitoxin.
It was like the inflammation hailed more immune cells
to come check out what's going on.
-They found that if you could add some substances
to these toxoids,
you could kind of do the same thing.
You'd get a better immune reaction from the body,
and those are called "adjuvants,"
and they're actually really critical to vaccines today.
-The adjuvant used in that first diphtheria vaccine
was the form of aluminum,
which is still in certain vaccines today.
It's not in the measles vaccine, but it is in DTaP,
which is one for diphtheria, tetanus, and pertussis.
The amount of aluminum, however, is really small,
and aluminum is in a lot of other products we consume,
including antacids and some baby formulas.
Additives are one of the most controversial topics
surrounding vaccines today, so, while we're on the subject,
let's talk about two other adjectives
that people get nervous about, formaldehyde and thimerosal.
Formaldehyde is used to deactivate certain germs
and also toxins, turning them into toxoids.
The vast majority of the formaldehyde is removed
before the vaccine is administered,
but a very small amount does make it
into the final mixture --
less than the amount found in a single pear.
Thimerosal is a mercury-based preservative
that's sometimes used to keep bacteria
from growing in the vaccine.
It's actually in very few vaccines today.
Some flu vaccines that do contain it have about
25 micrograms of mercury per dose.
That's the same amount of mercury
in a 3-ounce can of tuna.
But on top of that, the type of mercury found in thimerosal
is different than the type that can make fish dangerous to eat.
It gets broken down by our bodies far more quickly.
But if you're still concerned, you can get a version of the flu
vaccine that doesn't contain thimerosal at all.
There's a common misconception that thimerosal was at one point
in the MMR or measles, mumps, and rubella vaccine.
It actually never was.
In 2001, however, due to public fear
that thimerosal was somehow linked to autism,
it was removed from all childhood vaccines,
simply to reassure parents that vaccines were safe.
There was no scientific evidence at the time
that linked thimerosal to autism,
and since it was removed from those vaccines,
scientists have seen no decrease in autism rates.
In the late 1800s,
with advances in vaccine creation and microbiology,
it seemed possible to fight any illness.
Louis Pasteur famously claimed,
that it was "within the power of man
to eradicate infection from the Earth."
But, of course, that didn't happen.
We've made vaccines for many horrible illnesses,
but there are still more we haven't been able to crack.
However, new technology might be changing that.
To learn about it, I went to the Vaccine Research Center
at the National Institutes of Health.
-Classic vaccines have been incredibly successful,
but we've made the ones that are on the easy side.
The ones we don't have are the hard ones.
-Take flu and HIV.
They both evolve really quickly,
changing the antigens that coat them.
That's why we typically need to get a new flu shot every year.
-The influenza virus,
it's almost like it's dressed up.
It's wearing party clothes, and each year,
it sort of changes its outfit.
-That's exactly right, and, so, scientifically, we say,
"Okay, how does the virus work?"
It has to get into the cell.
What part of it does it use to get into the cell?
It can't change that.
But if we can be really smart, we can extract that part,
show the immune system that part of the virus
that usually is hidden, and we can make a response
that's more acceptable across all different types,
no matter how the virus changes its dress code.
-New techniques are also making it possible to create a vaccine
without even needing a weak or dead version of the germ.
Take zika, for example.
-So, that was a virus that we knew about,
but was pretty rare and only had occurred in a few places,
and all of a sudden, it took off and started to spread
through large populations and cause disease.
So, people went out in the field,
and they isolated just samples from people who were affected,
sequenced the virus,
and, actually, that sequence was sent to us digitally.
We never actually see the sample of the virus.
-The scientists could then take the gene that codes
for a particular zika protein and use that to make a vaccine.
If you inject only that gene into human muscle,
the muscle cells temporarily read
the DNA just like their own genetic code.
For a short time, they act like little factories
producing the harmless zika protein.
That allows the body to build up an immune response to zika
without a person
ever coming into contact with the virus itself.
Another new technique to make vaccines
that don't include germs is nanoparticle technology
where scientists can create a small particle in the lab
that looks like a particular virus.
-That's particularly useful for dangerous viruses.
If you think about ebola, for example.
We don't want to be dealing
with growing a fatal virus in a laboratory
or even using a classic approach like trying to kill that
and injecting a killed ebola virus back into people,
so we can use a virus-like particle or a nanoparticle
that looks like ebola virus.
-New technology like this could soon help us
prevent more diseases than ever before,
but when you make a new vaccine, how do you know it's safe,
and is anyone checking to see
if there could be any long-term effects?
In the next episode,
we'll learn how vaccines are tested for safety
and why there's been so much controversy over vaccines
and autism.