Health and medicine
- What is the flu?
- Catching and spreading the flu
- When flu viruses attack!
- Three types of flu
- Naming the flu: H-something, N-something
- Testing for the flu
- Antiviral drugs for the flu
- Genetic shift in flu
- Flu vaccine efficacy
- Flu shift and drift
- Two flu vaccines (TIV and LAIV)
- Flu vaccine risks and benefits
- Making flu vaccine each year
- 5 common flu vaccine excuses
- Vaccines and the autism myth - part 1
- Vaccines and the autism myth - part 2
- Flu surveillance
Learn about how the flu vaccine is made every year and how they name the strains that they put inside. Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Rishi Desai.
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- How exactly do you weaken a virus? What are the materials/chemicals used?(15 votes)
- These vaccines are produced by growing the virus in mammalian cell lines (or tissue cultures) which selects for less virulent strains or they can also be created by altering the expression of important virulence genes by targeted deletions or insertions into genes required for pathogenesis (i.e., rendering those genes dysfunctional). As you mention, weakening a virus through chemicals can be carried out as well, such as inducing DNA mutations through UV radiation) but these are usually to general to cause the intended effect.(11 votes)
- Why are eggs used for vaccine testing?(9 votes)
- I'm not complaining because I think it's amazing that we have a vaccine for influenza, but why isn't it perfect? Is there something stopping it from being 100% effective?(4 votes)
- Because it is always mutating to be resistant to the vaccine. :) That is why there is no cure yet.(8 votes)
- Do they have to weaken the virus that they add in the vaccine so the body does not just get sick ?(2 votes)
- Yes the virus is either weakened (attenuated) or killed completely. This means it can't make us sick but our immune system still learns what it looks like and how to fight it.
Virus can be killed using heat, radiation or chemicals such as formaldehyde.
Virus can be weakened (attenuated) by incubating it with another animal, or eggs, or cells in a dish. Over time the virus adapts to the incubator (e.g. a pig) and loses its ability to infect humans.(2 votes)
- I have been looking for information on how the influenza vaccine is made. After watching this video I still know very little about how the vaccine is made other than it is grown on eggs which I already know. Other websites like the CDC say the virus is "inactivated" well how is it inactivated? someone wave a magic wand or something? it is heated or treated with bleach or alcohol or what. And then it is "purified" but again zero information on what that means. what is purified away from what? and how is it purified? run through a filter or something? and what exactly in the vaccine? broken up pieces of virus, just H and N viral proteins, viral RNA? This video says "learn about how the flu vaccine is made..." Then there is about 10 minutes of talking but almost nothing on how the flu vaccine is actually made. Maybe Khan academy can make a new video about how the flu vaccine is made and then explain how it is actually made.(1 vote)
- When the flu vaccine is inactivated, it is usually done chemically with formaldehyde or betapropiolactone which inactivates viral toxins. Once inactivated the remaining viral components (which is basically just viral envelope at this point) are "disrupted" meaning broken down with a surfactant so the (H) and (N) antigens more accessible to the immune system.
When they say "purified" it means they are increasing the antigenic concentration (doing this makes the vaccine more effective) of the virus by removing material in the serum that may cause unwanted side effects (such as excess egg protein). This is typically done by zonal centrifugation which makes the serum components easily separable.
Here's a link to a chart showing vaccine ingredients:
- Does efficacy mean the chance that you are immune, or is it a less black-and-white thing? For example, is it possible that the vaccine increases somebodies resistance so that they are less likely to get the flu from a particular encounter, though not necessarily immune? If the later, does that mean that in a country like India or China where the population is denser and there may be many more encounters than say outback Australia that the efficacy is different?(1 vote)
- Even someone with an immunity can have their immune system overloaded if there is enough exposure to a particular pathogen at any given time.(2 votes)
- At7:00Rishi refers to the efficacy as 62% (and mentions efficacy in a few other spots). To be clear, does this mean the vaccine is 62% effective against all instances of the flu, or just 62% effective against the three selected strains (or something else again)?(1 vote)
- Just the 3 specific strains for efficacy, but do be careful because the terms "Efficacy" and "Effectiveness" for the Influenza vaccine are often used interchangeably. This page from the CDC is pretty comprehensive in how the studies are done. http://www.cdc.gov/flu/professionals/vaccination/effectivenessqa.htm(2 votes)
- I haven't had a flu shot in years, what is the effect of this?(1 vote)
- Well, you quite simply will have a higher chance of getting the flu than if you took the vaccine.(2 votes)
- If you get the vaccine a lot of times, like, for example, 5, would that be a lot of protection?(1 vote)
- You can only get the flu vaccine 1 per year. For example if you get the flu 2 then you will less likely get it again. So when your body detects a flu then it will fight it off. But the first time, your body doesn't know what it is so it doesn't know how to fight it off.(1 vote)
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.