- [Mary] I'm Mary Parker,

and welcome to this episode of
"Eureka: Sounds of Science."

(gentle synth music)

Vaccine boosters have been
in the news a lot recently.

While everyone is talking about COVID,

I started to wonder about

the history of boosters in general.

Joining me to answer
some of my questions is

Dr. Peter Matos, a consulting
physician for Charles River.

Dr. Matos worked previously
as a military physician

and for the US Department of Defense

Global Emerging Infection,
Surveillance and Response System.

He joined me recently in our video series,

"A Dose of Science," and I'm
glad to welcome him back.

Welcome Dr. Matos.

- [Peter] Thank you, Mary,
for that kind introduction.

Happy to be back here to
discuss the topic of vaccines.

- [Mary] Cool, and, you know,
now that I have you back,

before we get into the other questions,

I'm curious, what exactly is
the US Department of Defense

Global Emerging Infection
Surveillance, and Response System,

and could they have fit any more words

into the name of their department?

- [Peter] So GEIS is what the acronym is,

sits under what's called

the Armed Forces Health
Surveillance Center.

And their job is to be
an early detection system

for emerging infectious
diseases, such as COVID.

- [Mary] Well, they probably
had their work cut out for them

in the past couple of years then.

So... good luck to them.

My goodness.

So can we start with a
bit of a history lesson?

How did we discover that some
vaccines needed boosters?

- [Peter] Yeah, and a matter of fact,

almost all vaccines need boosters, right?

The one that comes to mind
that you don't necessarily

need a booster is smallpox.

Smallpox is unique in that
it's a sterilizing vaccine

and, most of the time, most
people you're going to have

a scar on your arm from where
you got your smallpox vaccine.

So outside of that,
almost all other vaccines,

and in fact, all other
vaccines require a booster.

So, you know, if you think
we're all adults, right?

If you get a really deep cut,
one of the first things we do

if you come to the emergency room is

we ask when was your
last tetanus shot, right?

So, like, for one of those things, right?

So it's every, you know,
you're going to need a tetanus,

you know, every 10 years.

If you have a really dirty wound,

they recommend every five years.

So most of the time your
immune system needs reminding.

And it's kind of like
the analogy I'll make,

it's like learning a language, right?

If you don't practice, you forget.

Well, the same is true
for your immune system.

If it's not reminded, it forgets.

- [Mary] Oh, okay.

That makes sense.

Well, do you know why, then,

the smallpox vaccine only needs one?

Is it, I think I have...

- [Peter] It's unique in that
it's a sterilizing vaccine,

meaning that it protects both

the individual that is
vaccinated and prevents spread.

Hence the term sterilizing vaccine.

And that's very rare in medicine.

- [Mary] Are there any other examples

or is that pretty much the only one?

- [Peter] No, that's it.

- [Mary] Wow.

I was going to say, my next question was

what are some examples of
vaccines that don't need boosters?

So I guess that's the only one.

- [Peter] That's pretty much
the only one to my knowledge.

- [Mary] Is that a product of
the vaccine being so awesome?

Or is it something to do with smallpox?

- [Peter] Both.

It's a product of the
vaccine, how it's delivered,

and then also the virus itself.

Kind of both the immunology and
the molecular biology of it.

- [Mary] Wow, okay.

So what is the secret to
the longevity of vaccines

that don't need boosters?

So well, I guess...

I'm going to reword this a little bit.

What's the secret to the
longevity of vaccines

that don't need frequent boosters.

I mean, most you might want
a couple the HPV for example,

but they only need it
every couple of years

and then you're done.

So is it, why are those
a little bit better

than say Tdap that you
need every 10 years?

- [Peter] Yeah so, I think one produces

a more robust and long
lasting immune response.

And I think the best example

that comes to mind is the MMR vaccine:

the measles, mumps, and
rubella vaccine, right?

You know, as a child,
we get multiple doses.

And then the recommendation is

that at some point over your lifetime,

you may require one or two doses

depending on what you're doing.

So let's say if you're traveling

to a country where the measles, mumps, MMR

is not widely utilized.

What I would do is, if you came
to see me in travel clinic,

I would get a titer

and see how strong your
immune response is.

And let's say your titer was low,

I would give you a booster.

With measles, mumps, and rubella,

it really depends on how strong
an immune response you get.

So maybe you only need one dose,

one booster in your lifetime

or maybe you need two
doses in your lifetime.

You know, the recommendation
is one to two doses,

depending on the
indication for the vaccine.

- [Mary] And you mentioned a
titer, what is a titer test?

- [Peter] Yeah, so that we
don't have yet for COVID.

A titer basically tells you

how strong your immune
response is to a vaccine.

And it also helps us understand

how long that immunity will last.

So the example is, you know,

I'm being a physician,
I get my blood draw,

you know, for measles, mumps, rubella,

and being that I was
born in the early '70s,

I did not have a chicken pox vaccine.

So I always have to get my titer drawn

for varicella, for chicken pox.

So that's the point of a titer.

So it tighter tells you the strength

of the immune response to the vaccine

and it also tells you the length.

Well, the problem here is that

titer is not set yet for
COVID-19 for instance,

because we don't have enough data, right?

It's only been around for, now,

a year and a half and some change.

And we need, that will be set over time

based on both, you know,
the immune response,

they'll come up with a curve,

and then we'll get data
over the next decade to say

okay, if you have these many immune cells,

this is how long your
COVID-19 vaccines should last.

Unfortunately, I think COVID

is going to be similar
to kind of like flu.

We are probably going to need
one every year, unfortunately.

- [Mary] So getting back
to the standard stuff,

how did we arrive at the
current recommended vaccine

schedule for children and adults?

- [Peter] Yeah so, over
many decades of study of,

you know, following
both children and adults

to see how long these vaccines last,

how long does the immunity
last in an individual?

What does that curve look
like both based on time

and the number of immune
cells based over time.

So that data has been built
up over the past 50 years.

And that's how we've kind
of come up with the schedule

for both children and adults.

- [Mary] Okay, and so
that's kind of the part of

the COVID puzzle, I guess,

where we can't really cut corners.

We can't go any faster.

We're just going to have
to spend time watching it

and seeing what happens?

- [Peter] Correct.

- [Mary] Yeah, that's
probably the frustrating part.

Some things in nature just take

as long as they take, I suppose.

- [Peter] Yes, that's exactly right.

- [Mary] (chuckles) So what
are some of the vaccines

and boosters that are recommended based on

the work conducted at Charles River?

- [Peter] Great question.

So I think one of them would be, you know,

just like for most
healthcare providers, right?

Hepatitis B, which used to be called

the medical students disease, right,

because medical students are
learning how to be physicians

and work with needles.

They would get pricked a lot.

So, hepatitis B would be one.

So any type of bloodborne illness.

The other would be any
type of respiratory virus.

If you're working with, you know, flu

or pertussis, you know, whooping cough,

if you're working with a
select agent like smallpox,

you would want to make sure
that you're vaccinated.

Those are some of the vaccines.

And then, of course, I think, you know,

the general vaccines that we
recommend to all adults plus,

you know, your annual flu vaccines.

I think those are the
things that, you know,

anyone that works at
Charles River should have,

and anyone that works
with bloodborne pathogens

should definitely have hepatitis B

and also the normal adult vaccines too.

- [Mary] I thought about having to

get vaccines when you travel.

I hadn't thought about
having to get vaccines

depending on your job.

- [Peter] Yes, you know, so for instance,

in the military, I think,
we have an anthrax vaccine.

That's pretty unique.

So, I'm not sure but if you
had people at Charles River

that worked with the select agents

such as, you know, anthrax

they would probably be
required to have that vaccine.

- [Mary] Do you think that eventually

a booster for COVID will be recommended

or is it more likely that we will need to

develop different vaccines
to account for the variance,

kind of like the flu?

- [Peter] So the answer is both.

So I think what we're going to see is,

I think the science
probably supports a booster

somewhere in the nine to 12 month range,

for fully immune competent individuals.

And for those individuals that are at risk

with a suppressed immune system, you know,

so anyone that has any type
of autoimmune disorder or

they're over 65, you know,
the Israeli data from Pfizer,

it looks like it supports
getting a booster sometime

in that six to nine month range.

That guidance is still evolving.

I expect that the FDA and
CDC will come out with

guidance for boosters
within the United States.

And remember a booster is
just a reminder, right?

It's kind of like a flashcard, right?

If I show you a flashcard
once, maybe you remember it,

but if I show it to you three times,

you're probably going
to have better memory

of whatever was on that flash card.

It's the same thing
with your immune system.

The more frequent boosters,

the more likely we are to
help your immune system

remember how to fight off COVID-19.

And it was an Israeli study,
specifically looking at

giving boosters to these at risk folks,

and they did find that
they were able to mount

a more robust and
effective immune response

against the COVID-19 Delta variant.

So I think boosters work.

Then you brought up another question

which is a new vaccine recipe,

or basically it's the same vaccine,

but with an updated spike protein.

And I think those will
probably be coming out

sometime this winter.

Best guess, based on what
I'm reading right now,

sometime in the December
to January timeframe

we'll have updated vaccines.

So I think there's two things:

one is a booster, which is pretty much

getting the same vaccine
that we got this past year.

And the other is a new updated vaccine.

And I think those will
come later this year.

- [Mary] I guess I hadn't thought about

the flu vaccine in terms of
needing FDA approval every year,

because obviously it doesn't.

Do you think that'll be
kind of similar for COVID

where you'll just get an
updated version of it each year?

- [Peter] Yes, that's exactly correct.

So it's the same vaccine, same components,

and we have all of the data on that.

What's new is just kind of

the molecular biology of what
is going into the vaccine.

So, you know, for example, one
year maybe your flu vaccine

is H5N6 with something else,

and the next year it's
H3N2 with something else.

And that's, you know,
hexidase and neuraminidase

which are like the binding sites for flu.

So, you know, something along those.

So maybe rather than spike protein 123,

it's going to have spike protein 567.

Something along those lines is

what we'll probably going to
see over the next few years.

You're gonna have a, probably
a yearly update for COVID.

- [Mary] That's actually kind
of comforting to think of.

We think of COVID as this
giant life-changing thing,

and it obviously has been.

It's changed the whole world,

but if we can integrate it into our lives

in the same way that
we do the flu vaccine,

then it actually seems like
we might possibly get back to

a sort of semblance of normal.

- [Peter] Yes.

- [Mary] That's good, that's good to know.

- [Peter] We'll get there.

- [Mary] (laughs)

- [Peter] Not as fast
as any of us would like,

but we will get there.

- [Mary] Well, science takes time.

And I think that if we've learned that

we've definitely learned
that in the last year.

- [Peter] Yes, for sure.

I think, you know, now that
we're not wearing masks,

people, aren't socially
distancing, you know,

we can expect a rebound of flu

and all of the other usual
respiratory illnesses such as,

you know, bacterial pneumonia.

For kids, respiratory syncytial virus.

We're already seeing a huge
increase in those things.

So I think this fall, it's very important

to not only make sure that
you've gotten your COVID vaccine

but also make sure that you
get your flu vaccine too.

I expect we're going to
have a very busy fall

for respiratory illnesses.

- [Mary] Yeah. People have been
wanting to get back together

with friends and family for a long time.

I could see that spiking even,

maybe more so than previous years.

Not, you know, understandably.

We're all desperate to see
our friends and family,

- [Peter] Yes.

- [Mary] But we need to make
sure that we are protected

and so are they.

- [Peter] Absolutely.

- [Mary] Well, thank you so
much for joining me, Peter.

This has been extremely
helpful and enlightening

and also kind of comforting.

- [Peter] Your welcome and stay
positive and get vaccinated.

- [Mary] Will do.

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