Articles, Blog

Making flu vaccine each year | Infectious diseases | Health & Medicine | Khan Academy

October 20, 2019

So the story begins with
the WHO, the World Health Organization. And the WHO actually works with
a few of the regional labs. So there are actually five labs
sprinkled around the world. And these labs collect specimens
from hundreds of countries. So hundreds and
hundreds of countries do surveillance to figure
out what type of flu is affecting their
particular population. And they will send
this information over to these five regional labs. And I’m just going
to quickly draw out for you where the
regional labs are. There’s one over here in the US. There’s also one
down here in China. And then there’s another
one over here in Japan. And a fourth one in the southern
hemisphere in Australia. And finally, there’s one
in the United Kingdom. So this is the last one. There are five in total. The WHO will take a look at
all the different strains that have come into these five labs
again from all over the world. And they’ll try
to make a decision as to what makes the most sense. Because flu usually
moves around the world in a very predictable way. So they can make
an educated guess as to what strains they
should include in the vaccine to protect people
most effectively. Sometimes they’ll use
a strain that they used in previous years. And sometimes they’ll
pick something brand new. So let’s go through
the three strains that they actually
picked for the most recent vaccine, the
2012-2013 vaccine. I’ll start with the type
of virus they put in there. And generally it’s two
type A’s and one type B. That’s the usual
formula that they use. The WHO recommends that for
the trivalent, or three strain vaccine. And the exact one
that they choose can be actually followed. They usually name it in
part based on location. So they’ll say,
OK, the type is A. And they’ll say the
location is– in this case, the first one actually
came from California. The second one came from
Victoria, Australia. And the final one came from
Wisconsin in the United States. So this is the location
of the three strains. In fact, if you
ever see it named, you’ll see a slash
between these two. So I’ll put a
slash here as well. Next, they actually
have strain numbers. So they’ll give you a number
and what that number refers to. It doesn’t mean a whole
heck of a lot to us. But we’re going to put it
in there just because that’s how they name things. The strain number is,
for the first one, 7. This is 361. And this is strain 1. And then finally, they’ll put
the year that they actually identified this thing. So the year of identification. And this first one, this
type A, was actually identified back in 2009. Whereas the other ones
are a little bit newer, identified in 2011 and 2010. So, that’s what comes
after the strain number. And finally, the
last thing, which only applies to the first
two, is that if it’s a type A, they’ll actually tell
you the H and N type. So, for example, the first
one, the California strain, this one is actually
a type H1N1. And the second one is an H3N2. And the third one,
because it’s a type B, we don’t really use that
H and N classification. So I’ll just put a hash
there, meaning nothing. So if you ever come
across these things in some sort of formal
document, at least now you know what the heck all these
numbers and words refer to. So this is literally how
they name the strains. And just for you and I to
know, this first one here, this one is actually
an old strain. So, this is actually part
of the last few vaccines. This is not a new one
that was included. Whereas these other ones
down here, these ones, are actually new strains. They were not part of the
vaccine in previous years. These are new additions
or changes to the vaccine. So just to remember,
we always include two type A’s and one type B.
And the type A’s, one is a H1N1 and the other is a H3N2. That’s how we’ve been
doing it in recent years. Now let me bring up a
little bit more canvas because I want to talk you
through exactly what happens once the WHO decides
that these are the strains they’re
going to use. And this decision was actually
made back in February of 2012. So months and months in advance
they’re figuring out what strain we’re going to use. And that information then
goes to the next group of folks, which is
the manufacturers. The manufacturers are going
to take this information and they’re literally going to
start putting things together. They’re going to start
the manufacturing process. And one of the key parts of this
process, which a lot of people don’t realize, and it’s
pretty mind boggling, is that you need
millions, actually hundreds of millions of eggs. The same kind of eggs you
might eat for breakfast. But these eggs are
actually laboratory grade and they’re needed for
making this process work. And once it’s made,
one of the key things, and this reassures a
lot of folks, is safety. We want to make sure that
these things are safe. And so a lot of testing
goes into making sure that all of these vaccines
that they make are safe. So once that’s done and people
feel comfortable that it’s a safe vaccine, we
start distributing it. So distribution is next. And we’re going to go
through each of these stages and think just a little
bit about which people are involved in all these steps. But I just want to lay
out all the steps first so you get an appreciation
for how many players there are and how many steps are in
getting a vaccine to you. So it goes, of course,
from distribution, it goes to these clinics. And then finally, at the end
of the day there is a person. There might be you. This is you getting
your flu shot and you’re very happy
because you’re now protected from the vaccine. And I’ll draw a little
shield around you, a little protection
for you, to make sure that it’s clear that you’re
protected– not completely– I’ll draw a little hole
in the protection– not completely because
a vaccine isn’t perfect. But it’s pretty good. And in fact, this year, in
terms of how well the vaccine is working– not in studies, but
in the real world– in terms of how it’s doing as
people are getting it– about 62% effectiveness. So it’s actually
really quite good. In studies we always
see around 60% to 70%. And now, in real life, we’re
seeing a 62% effectiveness in terms of vaccine
effectiveness. The word effectiveness
just means real world data, versus efficacy– is
what we see in studies. That’s the difference
in the two words. So let me list out some of
the different folks involved at each step of the way. So in terms of
selecting the strain, we said that the WHO is
responsible in working with all the different
countries and the public health groups and laboratories
and scientists that are looking at all
the strain data. And then in terms of
manufacturing, there you got to think about
the vaccine industry. There are many, many
big players here. Big business is
involved in terms of churning out millions
of doses of vaccine. So here the vaccine
industry is a major player. And then, you think of all the
other groups that are involved. So I said that you have to get
hundreds of millions of eggs to make this process work. And so of course, then you have
to really work with farmers. And if you have a year
where the flu is really hurting the birds and
the chicken population then that’s going to make
it really hard because there are fewer eggs to contribute
to the vaccine manufacturing. So it’s actually an
interesting thought process. Flu obviously affects
chickens as well as humans. And so if those populations
start dying out, then even humans suffer because
we don’t have the vaccine. Now, then safety is huge. So you have to think of all
the different countries that have organizations
that care about safety. And in the US the one
that comes to mind is the FDA, or the Food
and Drug Administration. So each country
has its own process of thinking about safety. And those groups are
obviously very involved in making the vaccine as well. Then you’ve got all these
logistic things to think about. I mean, if you’re making
hundreds of millions of vaccines, you’ve
got to distribute them around the world. You’ve got to think about
airplanes that can actually take your flu vaccine
and move it around. You’ve got to think
about refrigeration. Maybe ships if you’re moving
across large bodies of water. Maybe trucks to
get vaccine inland if it’s cheaper that way. So lots of logistical issues to
think about how to get vaccine distributed. And then finally, you’ve
got nurses and doctors in the clinics that
have to be informed. They need to know when to
start making appointments for their patients
and how to set up clinics to actually administer
the vaccine to all the folks. And finally we’ve got you. You’re at the end of this chain. And not just you, but there are
about 250 million folks just like you getting vaccines. So 250 million doses are
actually put together. And this is quite an effort. You can see the
countries involved. And getting all that information
to all these different groups that have to get
involved in terms of making this even possible. So, to me, this is actually one
of the most impressive feats out there. And it really is a
testament to what science can do for mankind.


  • Reply alexandrenr January 22, 2013 at 1:27 am


  • Reply robobrain10000 January 22, 2013 at 1:28 am

    250 million world wide? The US population alone surpasses that number.

  • Reply Vocaloidict January 22, 2013 at 5:24 pm

    So the whole world uses one vaccine?

  • Reply Ethan Glover January 22, 2013 at 8:06 pm

    Isn't proper nutrition MUCH more effective than shots? It works better for me.

  • Reply khanacademymedicine January 23, 2013 at 5:16 am

    Proper nutrition is incredibly important for a healthy immune system, normal healing, the list goes on and on… Unfortunately, the exact effectiveness (i.e. an actual number) of proper nutrition at preventing getting sick from the flu is incredibly hard to define or measure.

  • Reply AlexXFresh October 9, 2013 at 11:13 am

    Vaccines are a total pharmacy scam.

  • Reply jessica thompson November 16, 2014 at 12:34 pm

    This video is full of misinformation but most conflicting statements made were so call lab grade eggs , yet they come from farmers .. Ok that makes no sense

  • Reply Patrick Guenette November 22, 2016 at 2:34 pm

    Where does the WHO get the original virus strain? Do they come from samples taken from humans that have already been infected? I've always been curious about that and this video has not explained it.

  • Reply Cindy Boyer December 1, 2016 at 5:04 am

    Wish a radical would destroy all vaccines, so they would have to make safe ones. Then we wouldn't have all the autism. There are slot of 20 year old men still in diapers because of the CDC. They are predators, who don't care who they hurt.

  • Reply Kori Ditty February 14, 2018 at 8:03 pm

    So what is actually in the vaccines? The adjuvants found in vaccines stimulate our immune system. This could lead to auto immune disorders. I have read that there are animal and human by-products found in a number of vaccines. I don't think they are testing each individual ingredient to deem it as safe. I already have two auto immune disorders from all the vaccines I have had throughout my life. I will never get the flu shot or any other vaccine for myself or anyone else in my family

  • Leave a Reply