Antiviral drugs for the flu | Infectious diseases | Health & Medicine | Khan Academy

I'm going to quickly
sketch out a flu

virus for you--
something like this.

And it has an envelope, so
this is our little envelope.

And on the inside
of this envelope

are eight chunks of RNA,
so let's draw out the RNA.

This is the genetic material.

And this genetic material,
among other things,

codes for protein.

And so one of the proteins
here is sitting on the outside.

I'm drawing it as if it
looks like a little hand.

And the reason I do that is
because it reminds me that this

H stands for hemagglutinin, but
it basically holds onto sialic

acid .

And that's how it gets
inside of little cells.

And then there's another
protein over here.

And I draw these as
a pair of scissors

just to kind of remind me that
this one nicks the sialic acid.

This is called neuraminidase,
and it nicks the sialic acid,

and it helps it cut itself
loose from the cell.

And so it can move on
to other cells- kind of

helps with exiting.

And I haven't actually been
drawing this other protein.

There's another one here.

And I'm going to draw it now.

This is called an M2 protein.

But it's not actually
found on all flu types.

It's actually found
on flu A, but actually

not found on flu B. So this is
a really important difference

between flu A and flu B.

And you'll see why, because
one of the medicines that we

use now to treat flu-- and
yes, you heard me correctly,

that we do have
anti-viral medications.

You probably heard
from many people

saying antibiotics
only treat bacteria,

not viruses, and that's true.

But we have a special
word for these other drugs

that actually do treat viruses.

And we call them
anti-viral drugs.

And there are couple of them.

I'm actually going to write
out some of the names.

So this is called
Amantadine or Rimantadine.

And it's kind of
easy to remember

that they are in the
same class because they

share a lot of the same letters.

And these two anti-viral
drugs, they actually

work on stopping or blocking
the activity of this enzyme.

And I'm just kind of drawing
it like a little negative sign.

But that's just to remind
you that it blocks the M2.

So if you know that
flu B doesn't have M2,

then you also know
that these drugs then

don't work against flu B.

These drugs don't even work
that well against flu A,

because flu A has
become quite resistant.

So remember, resistance
happens because there

are little mutations.

And it turns out that flu A has
kind of a mutated form of M2,

so that it actually doesn't
get blocked by Amantadine

or Rimantadine quite so easily.

So unfortunately for
us, that's bad news.

And the CDC in 2012,
2013 have recommended

not using these
drugs because there's

so much flu A resistance.

So that's unfortunate,
but the good news

is that we actually have
a couple of other drugs.

So we have a drug
called Oseltamivir,

and related to
it-- and you'll see

with the spelling--
we have Zanamivir.

And these, of course, share a
lot of the same letters again.

And these two actually
block the neuraminidase.

And this is actually
in flu A and flu B.

So that's good news, because
it blocks both flu A and flu

B. And let me actually just
write that down, flu A and flu

B. And that's important, right?

So we have these two drugs,
and one of them is a pill.

This first one is a pill.

And the second one is
kind of an inhaled powder.

So they're taken
in different ways.

And another important
difference between them--

this is something that we have
to just kind of keep in mind--

is that there are
age restrictions.

So you have to be
a certain age to be

able to take these medications.

And they differ
between the two drugs,

and whether you're
using it to treat,

or if you're using it to prevent
getting sick from the flu.

There's a difference there too.

So there are age
restrictions that we just

have to keep in mind.

But overall, I'm pretty
happy with the fact

that at least we
have these options

if we need to treat someone
that's very sick from the flu.

So let's talk about
that treatment then.

So what if you have someone--
and this happens to me all

the time where someone comes
in kind of frowny faced

because they're sick with
the flu, and you're thinking,

OK well, this person
obviously needs treatment.

So I'm going to write
that at the top.

They need some
sort of treatment.

And I guess the
first question is,

why would I treat this person?

Of course, everyone's
going to be frowny faced

if they get the flu.

So why am I treating
this person?

What makes them so special?

Well, one thing that
could make them special

is-- let's say that
they're high risk.

Remember high risk groups in
our society, in our community,

include real young
kids-- so let's

say under two years
old-- or older folks--

let's say people
over 65 years old.

It could be someone
that's pregnant.

That's another high risk group.

Or it could be someone that has
some sort of chronic disease.

And that could be like a
lung disease or asthma,

any sort of chronic disease
that makes them ill.

Maybe their immune
system isn't working.

And that would be a
group I would definitely

consider treatment for.

Now another group-- I'm
going to put it just right

below-- is let's say
you have someone that's

completely healthy-- young,
healthy person, not pregnant.

They still might get
treatment if there's maybe

severe disease.

Let's say they get
really, really sick.

They're just feeling awful,
and I'm worried about them,

and they might need
to be hospitalized.

If they're very,
very sick, or they

get some sort of
complication, or they're

going to get hospitalization,
anything like that,

then this is a person, again,
I would be careful with.

And I would consider treatment.

Let me bring up a
little bit of space.

So this is the kind of group
that I would definitely

consider treatment in.

So what else should we
think about or consider?

Well, the next question,
often, that comes up

is how soon do you need
to start treatment?

When do you need
to begin treatment?

Or when do you start?

And of course that
answer's going

to be as soon as possible.

But a bigger range on that
would be within two days.

So really, if they've started
getting symptoms a week ago,

I might still be
inclined to treat them.

But I'd be more inclined
if it had just started.

What other questions
or considerations

should we just
kind of go through?

What about treatment?

So how long do you
treat them for?

And generally speaking,
it's about five days.

So five days of either
Oseltamivir or Zanamivir.

And sometimes it goes
a little bit longer,

but usually it's just five days.

That's kind of a normal course.

So this is how I
would manage someone

that's being treated for flu.

But of course, what if they're
not being treated for it?

What if they come in,
and they're feeling fine?

And we have to draw
another face here.

This is a smiley face,
something like that.

And I'm going to draw two.

So let's say there's two.

And we're going to deal
with them separately.

So let me actually draw
a line between them,

something like this.

So we've got two more cases.

Both are feeling fine, but
they might need prevention.

Another thing these drugs
can do is prevent you

from getting sick.

So prevention is
important as well.

And let's say these folks
are living in a home.

Let me actually build
a little nice house

around my first
smiley face person.

And I'll do the same around
this second smiley face person.

And let's say this
first person--

this person gets a
visit from someone

who's feeling flu symptoms.

So this person comes to
visit, and our friend,

our smiley friend, is worried.

They think, oh my gosh,
now I'm going to get sick.

So if they're high
risk-- and we went

through some of the
categories-- actually,

I should mention there are
other categories, not just these

that I listed.

There are some others as well.

But if they're high
risk in some way,

then I would
consider giving them

a medication like
Oseltamivir or Zanamivir

to prevent them
from getting sick.

Now this whole bit about severe
disease or hospitalization--

this doesn't really apply
because they're not sick.

They're obviously not going
to have severe disease

or hospitalization already.

What about this question of
when would I start treatment.

Well ideally, again, it's
going to be within two days.

So within two days
of their exposure.

We call the visit,
or whoever kind of

made them worry that
they might get the flu,

we call that the exposure.

And so really you want to start
treatment within two days.

And you also want to start
prevention within two days.

So how long would you actually
give them the medications for,

to prevent them
from getting sick?

Well it really depends
on whether or not

they've had the vaccine.

So let's say they've had the
vaccine, the flu vaccine.

And they were high risk.

They got visited by
someone, or had an exposure.

For this person,
I'm thinking I want

to treat them for two weeks.

Or give them two
weeks of medications.

And the logic is that if
I kept them two weeks,

then that basically covers them.

And then after
that, I would assume

that the vaccine would
kind of take hold.

Because remember, the
vaccine takes two weeks

to really take full effect.

So basically, I give
them a medication

during that period of time when
the vaccine isn't completely

protecting them.

And then I expect their
vaccine to kind of take over,

and for the rest
of the flu season,

presumably, they should
have good protection.

So that would be my strategy.

Now let's say that they can
not take the vaccine, so

no vaccine.

And maybe this person
has a severe allergy,

or had a horrible
reaction to the vaccine.

For whatever reason, they
cannot take the vaccine.

Well in this person, if
they can't take the vaccine,

or don't have the vaccine,
then for this person

I would actually treat
them for just one week.

One week after exposure.

So if the exposure
happened, let's say today,

I would basically--
and then let's

assume it's not going
to keep happening--

so one week after exposure
would then make it next week,

is when I would
stop the medication.

So in this scenario,
I'm protecting them

with the medication
against getting sick

from this exposure.

But because they've
had no vaccine,

if they have ongoing
exposures-- let's

say they get exposed again
to flu in three weeks-- then

again they'd have
to come back to me,

and we'd have to do
this all over again.

So it really is ideal to have
that vaccine in your system

to keep protecting
you and preventing you

from getting ill.

Now in this second
scenario, let's say

instead of having a
visitor who's sick,

let's say you've got people
around you that are sick,

living in the same place as you.

Now this person is obviously in
the home with a group of folks.

So let's call that a group home.

And what we call this scenario
is basically an outbreak.

So this person is living
in an outbreak setting.

And many, many people with
flu are living together

causing an outbreak to happen.

We really are worried
about other healthy people

like our smiley faced friend
from getting sick with the flu

as well.

So in this setting,
who am I worried about?

Who do I want to make sure gets
medications to prevent them

from getting sick?

Well, we've got high risk
people, again, living together.

So if people are
living together--

and this could be
senior citizens,

or could be a chronic care
facility, or nursing home--

and really any kind
of group setting

where people are
institutionalized

and they're high risk,
I'm going to be worried.

And I want to make sure
that we consider prevention

with one of these medications,
the Oseltamivir or Zanamivir.

And do I have to worry
about severe disease

or hospitalization?

Well, no, again because
here specifically

I'm talking about
the healthy person

who happens to be
in an outbreak.

So they're still healthy.

They're not hospitalized.

They don't have
severe disease yet.

So the whole idea
is to make sure they

don't get those things, right?

And when would I
want to treat them?

Well, it's hard to really
say within two days

because that implies that
something specific is

happening.

When in fact,
during an outbreak,

you just have constant
exposure, right?

I mean, everyone
around you is sick.

Let's say you go down
to eat in the cafeteria.

Everyone is sick.

So when you're having
constant exposure,

we don't really think
about within two days.

It doesn't really
make sense here.

So here I would just
kind of be worried

in general about this person.

And as far as
treatment, you really

end up just treating everybody.

Vaccine or no vaccine,
you treat everybody

throughout the outbreak
because the whole goal here

is really to minimize
the outbreak.

You don't want people to have
all the horrible consequences

of flu.

Remember, flu can kill people,
and can cause hospitalizations.

So to prevent all that,
because it's a high risk

group of people living
together, you would really just

treat throughout the outbreak.

And even one week after the
last case of flu is found.

So here, unlike
the scenario where

you have just a single
exposure, because you

have so many people in
an outbreak that are sick

and kind of exposing
each other, you basically

just treat everybody with
Oseltamivir or Zanamivir.

So now you see we have a
couple of anti-viral drugs,

and you see when we can
use them to treat folks,

and also when we can use
them to prevent folks

from getting sick.