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Two flu vaccines (TIV and LAIV)

Understand the differences between TIV (dead virus) and LAIV (alive, but weakened virus) and who should get which one. 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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Video transcript

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.