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Two flu vaccines (TIV and LAIV) | Infectious diseases | Health & Medicine | Khan Academy

November 4, 2019

So let’s say you go out
to get your flu shot. One of the first things
you’re going to realize is that there are two types
of flu shots available. I’m going to go through
them one by one. So the first one is called TIV. And TIV stands for Trivalent–
trivalent refers to the fact that there are three strains–
Inactivated– inactivated means that the strains are all dead–
Influenza– because of course, there are three
strains of influenza– and V is simply Vaccine. So this is what TIV stands for. And on the other
side, we have LAIV. And this one stands
for Live Attenuated– so this one is a live
virus, but it’s weakened. Attenuated just refers to
weakened– Influenza Vaccine. So just like the other one,
it has the same three strains. We don’t put different
strains in this one. And it’s live and attenuated. So let me actually
just take a moment to step back and talk about
this word “attenuated.” Specifically, you might also
hear the word “cold-adapted.” And what they do is they
literally chemically change the virus around, they
kind of modify it, so that it’s still alive. Technically it’s still
alive, but it can really now only cause
problems in your nose, because that’s the
only cold area. So the word “cold-adapted”
kind of refers to the fact that it’s only going to be able to
cause problems in your nose. And so if the virus goes deeper
into your body, where it’s now warmer, it will not
have any effect. So the virus can
cause a runny nose. It might cause a
little congestion, and sometimes it does for
people that get this vaccine. But it won’t cause any
problems in other places. So in your throat, you’ll be OK. In your lungs, you’ll be OK. Because it’s weakened. So let’s start back with TIV. This one is dead
and it’s injected. And in adults, it’s usually
injected in the upper arm. So if you see a picture of
people getting injections, you know this is the
one they’re getting. Right? They’re getting injected
usually in their deltoid muscle. And in contrast, the LAIV,
we said, was alive but weak. And we also give this
one in a different way. We actually squirt this one. It comes in a liquid, and this
one gets squirted in the nose. And that makes sense
because the virus naturally would go into the nose. And so this one we
give that way as well. So now let’s think about groups
that cannot get these vaccines. Which groups would we say no to? And the only group
really on this side would be anyone that’s
less than six months. So if they’re less
than six months old, they should not get
the TIV vaccine. I’m actually going to
just draw a dividing line between these two. And on the other side, for the
LAIV, who would we say no to? This group is a
little bit larger. So here, you would say no to
anyone less than two years, or– I’ll put a big or here–
or if they’re over 49 years old. So a 49-year-old is OK. But let’s say they’re 50, then
you would not give the LAIV. That’s kind of the cut-off. Also on this side
are pregnant women. So pregnant women should
not be getting this vaccine. And people with
chronic diseases. So let’s say you have asthma,
or you have kidney disease, some sort of a chronic disease
that you take medications for. You should not be getting
the LAIV if that’s the case. Now there are some others
actually in this group as well. I’m not going to go
into all the people that you would not
want to get LAIV. There are a few other groups. But I wanted to
point these four out because these are probably
among the most common. And an interesting
thing about this is that remember when we
talk about high-risk groups for influenza, we talked
about some of these. We talked about pregnancy as
being a high-risk group, people with chronic disease, very young
kids, and also the elderly. And of course, the
elderly would be a subgroup of this
over-49 group. And these folks, let’s
remember, these folks are at high risk of getting
problems or complications from flu. So they’re the group
that you really want to make sure you vaccinate. And as it turns out,
all of them are probably going to need the TIV, the
one over here, vaccine. Now let me make a
little bit more space. And let’s talk about a few more
groups or things to consider. Let me just kind of
leave this space here. Now, whenever I’m
giving vaccines, I always want to keep
in mind that there are a few questions
I should ask people. And if they answer these
questions in a certain way, I’m going to hold off
on giving the vaccine. So who would I want to hold
off on giving the vaccine to? Well one group, and this
might sound kind of obvious, but one group is someone
that’s had a bad reaction. Let’s say they’ve had a
bad, a severe reaction in the past to the vaccine. If they’ve had a severe reaction
or an allergic reaction, maybe, to the
vaccine– all right? Allergy– then that’s
a person I may not want to give vaccine to again. Right? I’d just want to clarify
what was the cause or what happened exactly. But if it turns out
that they didn’t respond well to it, either the
vaccine itself or to eggs, actually, because the vaccine
is made using eggs– and so either of these things. If they have an allergic
reaction or severe reaction to eggs or vaccine
in the past, I’m going to hold off
on giving vaccine. What’s another
group you might want to hold off giving vaccine to? Well, there’s a
syndrome out there, and you may not
have heard of it. But I’m going to
write it out here. And we’re going to just
kind of briefly discuss it, called Guillain-Barre. Kind of a Frenchified
pronunciation. And Guillain-Barre syndrome
is a problem of the nerves. So it’s actually a
nerve disease, basically a disease of the nerves
that causes muscle weakness. That’s how I usually
kind of explain it to people that want to know
what is Guillain-Barre. How is this muscle weakness? And there’s a relationship in
the past between people getting Guillain-Barre and the vaccine. That’s why we always
want to ask people if they have Guillain-Barre. And if they do, I would hold
off on giving the vaccine in most circumstances. Now a third one, and this is
probably the most common issue that I’ve seen come up, is
when people are moderately ill. So sometimes people
come into the office, and they say, well, you know,
I’m here for my flu shot. And it turns out
that they’re having a lot of fevers and chills. And so if they’re having
any sort of moderate illness or if they’re looking moderately
ill, then I would not give it. Now I say moderately,
and I’m trying to write this on
purpose this way, because if they have a mild
illness, a very mild illness, then it’s OK. So this is kind of a
judgment call, right? So you have to actually, as
a doctor or a nurse giving the vaccine, really think
about what is the illness and is it severe enough
to really make you want to hold off? So mild illness is OK. And that would be something
like maybe a runny nose or a diarrhea that’s very mild,
something that’s not too bad. So now you know
the two vaccines, you know who you
don’t give them to, and you also know some
things that we always kind of ask to make
sure and think about before we give the vaccine,
things to kind of hold off on. So let’s actually go down and
kind of test our knowledge. I actually wrote out a simple
example of flu clinics. So let’s say there’s
a flu clinic going on, and you’re in charge. So let’s take a look
at what you might do. This person in white,
this is you, right? This is you, and you’re
smiling because a lot of people showed up to your flu clinic. So you’ve got to go through. And let’s go one by one, and
figure out who would get what. So the ages of the
people are on top, and any kind of
illness they have or any kind of
chronic condition they have is written on the bottom. So let’s go through all
these folks one by one and figure out if they
can get TIV or LAIV. These are the two vaccines. And I’ll put a yellow
check if it’s OK, and I’ll put a red
x if it’s not OK. So the 3-year-old
and 1-year-old are brought in by their
62-year-old grandmother. And all three of them are OK
with getting the TIV, right? Because they’re all
over six months, and they don’t have any illness. They don’t have
Guillain-Barre, and they have no evidence of
allergies in the past, otherwise I would
have written it. So that whole family
is OK with TIV. What about the next couple? I’ve got a man a woman,
and the woman is pregnant. Well, both the man and the
woman are over six months. And the woman is
pregnant, but that’s not an issue with this vaccine. And the man has asthma,
which is a chronic disease. But again, that’s not a
problem with the TIV vaccine. What about the last family,
the 46-year-old woman and her 12-year-old son? Well, she has the flu, and
so she’s moderately ill. I would not give
her the TIV vaccine. I would hold off. Her son, on the other
hand, has mild diarrhea. So if he has mild diarrhea,
he’s still OK to get TIV. So that’s basically
what it would look like if I was
only giving out TIV. But, of course, I’m
giving out LAIV as well. So some people
may want that one. So let’s go through again,
and now think about LAIV. Well for the live vaccine, you
have to be over two years old. So the 3-year-old’s OK. But his 1-year-old
sister is not OK. So she’s too young
to get this one. And you also have to
be 49 years or younger. You can’t be over
50, or 50 or older. So grandma, who brought
them in, is also not OK to get this vaccine. So in the first family,
only the 3-year-old can get that vaccine. Now in the second family,
we’ve got a man and a woman. And the woman is
pregnant, so we know that’s going to make her
ineligible for this vaccine. And the man has a
chronic disease. He’s got asthma, so he also
cannot get this vaccine. In the last family, we have a
woman who is 46 and her son. Now the woman has flu. So just as before,
for the same reason, because she’s got
an illness, I’m not going to give her
this vaccine either. And her son has a mild diarrhea. And in this case, just as
before, if he can get the TIV, he also can get the LAIV. Because he’s not chronically
ill with anything, right? Now as a final point,
it’s a really great idea that this boy is going to
get flu vaccine because he’s around someone who has flu. So you want to try to prevent
him from getting sick as well. So he can’t really avoid
being around his mom, so it’s a good idea for
him to get vaccinated. And the vaccine usually
takes about two weeks to take full effect. So he has to wait
two weeks before he gets the full protection. But of course, along the way,
it’s going to kind of slowly creep up, and hopefully,
he won’t get sick as well.


  • Reply eilan damyr July 2, 2013 at 4:33 am


  • Reply Cliff Moore July 25, 2013 at 3:35 am


  • Reply PCAl oanz July 25, 2013 at 4:30 am

    Good one

  • Reply hug irked July 25, 2013 at 5:54 am

    Its sweet 🙂

  • Reply PsychicsHookup July 26, 2013 at 5:26 am

    Thats incredibly good…

  • Reply camphound July 29, 2013 at 9:36 am

    Thats impressive…

  • Reply grass bobbin August 13, 2013 at 7:18 am


  • Reply sarbasov August 16, 2013 at 8:29 pm

    How can virus be dead or alive if it is not alive in general?

  • Reply Minder winter August 17, 2013 at 5:35 am

    Its amazing

  • Reply wired worx August 17, 2013 at 8:56 am


  • Reply poppy wellmade September 10, 2013 at 4:15 am


  • Reply Whoosh Good September 11, 2013 at 8:59 pm

    thats great

  • Reply wired worx September 13, 2013 at 4:34 am

    Its interesting

  • Reply placidheart September 20, 2013 at 9:24 am


  • Reply BinaryOptions Guru September 28, 2013 at 4:55 am

    very good

  • Reply earthdamp October 7, 2013 at 3:55 am

    Thats very good

  • Reply wired worx October 15, 2013 at 9:42 am

    Good one

  • Reply wired worx November 7, 2013 at 2:47 am


  • Reply wired worx November 21, 2013 at 4:43 am

    Good one..I like it

  • Reply camel axel December 19, 2013 at 9:27 am


  • Reply camel axel December 19, 2013 at 9:36 am


  • Reply mortician pale January 17, 2014 at 5:30 am


  • Reply cadge sore May 9, 2014 at 10:21 am


  • Reply MiaVLOGSwithCreamy creamyloveforever October 10, 2017 at 2:37 am

    NEVER EVER NEVER get the live one you could FRIKING DUE

  • Reply Eull Light April 8, 2018 at 4:10 pm

    What a great illustration thank you so much ,I have a question when you say the tiv is dead/killed viruses, what kind of "death" is it ?
    In your other video about vaccine production you said it's done within eggs. I was asking if the virus is dead how can for a virus to replicate inside an egg?
    I could fly of happiness if you reply me back I was searching for hours

  • Reply Anyana B December 16, 2018 at 3:36 pm

    It fascinates me how different are educational videos made by physians and scientists. I can clearly see that the author is a practicing physician, there are no clear details on how the vaccine works, no reference to molecular mechanisms or how is the vaccine manufactured. The focus is clearly on patients, symptoms and decision making in administration. Being a science student myself, I actually found your video suprsingly relieving, thanks!

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