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
Many people choose to avoid the flu vaccine each year. Review five popular excuses, and how they relate to common misunderstandings about the flu. 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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- At4:06, I've always wondered how a form a virus can be dead for a vaccine. I've tried to look this up several times before but haven't found a concrete explanation. I've learned that virus's do not obey the Cell Theory, for they are acellular, and thus, considered not alive. How are flu vaccines made? What is done to the virus to render it dead/very weak for use in a vaccine?(5 votes)
- So-called 'dead viruses' are inactivated with formalin. 'Dead' viruses cannot take over the cellular machinery, so they do not reproduce.
The other type of vaccination is attenuated (so-called 'live virus'). Attenuated viruses can infect cells and reproduce but they do not cause disease.
Read Wikipedia for information about the two types of polio vaccination.
- Flu vaccine made me sick! The gentleman meant life-threatening allergic reaction....what then? How do I know if I am allergic to vaccines? And what about high mercury or aluminum level when taking a shot? Is it researched well enough to say they are safe and don't cause autism in a long run? Is it possible to make vaccines without poisons like mercury? I know that even small amounts could have dangerous side effects when injecting it to a small baby...and one more question, is it necessary to make vaccination compulsory?(0 votes)
- "How do I know if I am allergic to vaccines?"
The flu vaccines are prepared using chicken eggs. If you are allergic to eggs, it's probably a safe bet that you would be allergic to the vaccine.
"Is it researched well enough to say they are safe and don't cause autism in a long run?"
A well-respected medical journal published a study a number of years ago that connected autism to over-vaccination. The journal has since retracted this study which has received a lot of criticism. We do know that autism rates in the developed world are much higher than the non-developed world, but vaccinations do not seem to be the culprit.
"...is it necessary to make vaccination compulsory?"
That's an interesting dilemma and an issue that is being debated in many medical/political forums. If you're a traveler, some countries insist that you have particular vaccinations.(11 votes)
- I still got sick excuse - there was a Canadian study that found that people who had had the flu shot and got H1N1, were more likely to have severe complications (hospitalization). Do you know this study? Is anyone studying this phenomenon? Also, what about the link to Guillain barre syndrome.(4 votes)
- why do we need excuses to get a vacine?(3 votes)
- How would you know that vaccines don't have thimerosal?(2 votes)
- If you're concerned about a specific vaccine, the best way to know is to ask your doctor. The doctor recieves data sheets on each vaccine, that lists if preservatives, including thimerosal, are used in the vaccine. There are thimerosal-free vaccines on the market, and you can request them from your doctor. They may be more expensive, though.(3 votes)
- For those who choose not to have the flu vaccine simply because of pain, that's nothing compared to having a needle stick inside your vein and have your blood drawn!(1 vote)
- Actually I've had little pain from either needle stick. Maybe I've been lucky with who has been doing the sticks. And we need to keep pointing out that any pain associated with a shot is far less than the prolonged discomfort you'd experience with the flu.
I admit I look fixedly somewhere else during both sticks!(2 votes)
- At4:20, Rishi says the LAIV can't cause you to get sick. If you had a really weak immune system, couldn't you actually get sick? Thanks in advance.(1 vote)
- There are some groups of people (those with asthma, etc.) who do not qualify for the live vaccination. These people should get the killed vaccine.(2 votes)
- How can your body learn to fight the flu effeciently from a dead virus injection and be building proper T-cells as well...as opposed to fighting the real thing. When a virus enters your body it's alive and kicking and fighting...when you shoot it in it's "dead". The immune system can't be working the same...sure there is an invader but it's not fighting...so why would there be a need to call in more toops (build more immunity)? How can you get just as strong like that . Please explain and provide any research to support(1 vote)
- The viruses and your immune system don't literally "fight". The viruses have ways to hide, and to avoid capture, and the immune system has specialized cells that recognize and absorb the viruses. Having a live virus "kicking and fighting" in your body gives the virus more chances to evade the immune system, to cause more symptoms (make you sicker) and possibly, to overwhelm your immune system so that it will not be able to clear out the viruses before you die from the illness. With a killed or weakened virus vaccine, the virus holds still so that the immune system can identify the virus. Then, when your immune system encounters the virus again (maybe you shake hands with someone who has the flu) it is able to almost immediately attack the virus, and clear it from your system before the virus can cause illnesses.
I do not have the references with me, but there are studies that show a live, weakened virus, does provide a better immune response than a killed vaccine. However, some of the diseases we vaccinate against (small-pox, whooping cough, mumps) can kill you or have serious side effects. That's why we do vaccinate against them, instead of depending on exposure to develop immunity.(2 votes)
- Would getting a vaccine temporarily lower your immune system while it is fighting off the weak or dead virus?(1 vote)
- Vaccine is designed to be dead or weak virus to teach your immune system how to fight a stronger version of that virus. Unless the person suffers malnutrition or HIV it is unlikely that his or her immune system is affected.(1 vote)
- Do people really avoid the flu vaccine? I thought it is the law to get the vaccine.(1 vote)
- Yes, some people do avoid vaccines due to misconceptions or personal beliefs. No law requires one to get a flu vaccine.(1 vote)
Whenever I talk about flu vaccine with people, I often hear the same questions and comments coming up over and over again. And so I put a short list together of really common things that people say. And I wanted to discuss them one by one. So let's say this person over here to the top left, this person, she says to me, well, you know what? I don't really see the point of getting the vaccine because I never get sick. She says many years have gone by, and her immune system has just been really healthy, and she just never seems to get sick. So she just doesn't see the point of getting the vaccine. And in response to this, what I usually draw an analogy to is seat belts. And I'll say, well, many people have never been in a serious car accident, but we know from research that seat belts are a really good idea, and they keep you safe. And they reduce the risk of getting a horrible injury. And so just as I would recommend you wear the seat belt, or maybe you wear a helmet if you're doing something dangerous, similarly, I would recommend the flu vaccine. And usually when I explain it this way, people get it. And they say, oh, OK, well even though I've never gotten in a major car accident, I do wear my seat belt. So just like that, even though I've never gotten sick, I'm going to go ahead and get my flu vaccine. Now, on the bottom left, this gentleman is saying a little bit of the opposite. He says, well, you know, I've gotten the flu vaccine, Dr. Desai. But I still got sick. I did it last year, maybe the year before, and I still got sick afterwards. So what was the point? Why did I even do it? And so now I don't want to do it anymore. And I can understand his logic. That makes a degree of sense. And what I usually tell folks that say this is-- I explain the idea of a copycat virus, that maybe when they got sick with what they thought was the flu or the flu virus, that maybe it was one of these other viruses. Remember there are viruses such as RSV, or rhinovirus, that can sometimes make you feel like you have the flu. So maybe he had one of those viruses instead. Another explanation could be maybe he got sick right after he got the vaccine. And remember, the vaccine needs a couple of weeks. There's a two-week delay or so before you get the full protection from the vaccine. So maybe he was in that two-week time span right after he got the vaccination, and maybe he got sick then. And lastly, we have to remember the flu vaccine has three strains in it. So maybe he had a different strain. Maybe it was just one or the other flu virus strains that was out there that year. So who knows exactly why he got sick that year that he says he got sick. But that doesn't change the fact that the flu vaccine is still going to reduce his chances of getting sick in the future. Now, one thing, I'm going to stick with this gentleman here in the bottom left. He might say, well, a different strain? What the heck? If that's the case, then what's the point? I often hear that. He says, what's the point if you could have a flu illness from some other strain? And when people talk about this, I have to remind them that it's not perfect. So it's not an exact science. And what you have to remember is that it goes back to the seat belt issue. It does reduce your chances of getting sick from the flu, but it's not going to reduce it down to zero. Nothing in life is going to reduce your chances to zero, and there's still a possibility that you could get sick. And so our best offer is that you can reduce the chance of getting sick. Let's move on to this gentleman in the middle then. And so he says to me, well, you know what? I think that the flu vaccine made me sick. So this is a little different. He's saying that the flu vaccine itself made him sick. And this is something a lot of people think. They think, well, maybe I was fine, and maybe it was only after getting the flu vaccine that I got sick. And this can be a very frustrating thing to feel. I mean, that's horrible that you were feeling fine, and then a vaccine came along and made you feel awful. But a couple of facts have to come to mind. So one fact, for example, is that we know that the flu vaccine cannot give you flu. So we know flu vaccine does not cause flu. That's a fact. And the reason I can say that with certainty is that one of the two vaccines is actually dead. Remember, there's the TIV and then there's the LAIV. The TIV is a dead vaccine, meaning the virus inside of it is dead. And the LAIV-- that's the other option-- this one is alive, but it's very weak. And so usually with this one you might get a runny nose at best. And so, if he says, I think that I got sick from the flu vaccine, I would say, well, I don't think that's possible from this one, right? If you got the injected version, then that's not possible at all. And if you got the live version, then you may have gotten some symptoms, but we wouldn't call that the flu. And I would also say that if that weak vaccine made you sick, can you only imagine how you would have felt if you had the wild virus, the one that circulates and we're trying to protect you from? What's much more likely for this gentleman is that he probably got sick from maybe this copycat virus, one of the other viruses that are circulating, probably around the time that he had the flu vaccine. So he mistakenly thought that the vaccine made him sick when it was probably just another virus. Or maybe he got sick when he was still within two weeks of getting the vaccine. Because, again, we said before that it takes a couple weeks to really get up and running. So in the top right, now we have this guy and he says to me, well, you know what? I hate pain. And this is probably my excuse. This is the one I used to use a lot. I hate pain. And I hate getting vaccines because usually that means a lot of pain. So for folks like this, and again, this was my own mindset, I say, OK, well, if pain is what you're trying to avoid, think about the fact that flu, getting sick with the flu, is much, much worse than getting a sore arm. And that's the most common side effect people talk about with that TIV vaccine, the dead vaccine. And also, if you get the other vaccine, the live vaccine, then I would say, well, flu is still a lot worse than getting a runny nose. And that's the most common side effect that people talk about with the live vaccine. So when you think about the common side effects, flu is much, much worse than the side effects you get with the vaccines. So we come down to this lady in the bottom right. She says to me, well, you know what, Dr. Desai? I think you're a nice person, but I really don't trust vaccines. I don't think that they're safe, and I don't trust what's inside of them. I think that there is something dangerous about them. And specifically, I don't like, she might even say, thimerosal. Thimerosal is something that people talk a lot about. And it's found inside of some of the flu vaccines. And so that's what she's referring to. So, in response, it's tough. It's tough to talk about issues if you're not trusted. And so the first and easy thing to say is, well, if you really just don't trust thimerosal, some of the flu vaccines, the single-dose kind of vials of flu vaccines, they don't even have thimerosal. So single-dose vials don't have thimerosal. So that's kind of an easy solution, right? If that's her biggest issue or concern, then you can just say, well, fair enough. That's an easy fix. And sometimes that works. Sometimes that's good enough and people say oh, OK, well, if they don't have it, then I'll go ahead and get the single-dose flu vaccine. But for others that simply just don't trust vaccines in general, because they've heard about thimerosal, or they've heard about autism, things like that, there I think it's really helpful to just discuss where these things come from. Where did this whole idea of thimerosal or autism-- where was it born? And the truth is that there's a complicated history to that. And there's a huge thimerosal myth that has been born and people discuss on the internet. And so I'll talk about thimerosal myth and the facts behind it because that's the only way to garner a little bit of trust with folks, is to actually discuss the facts. And actually separately from this video, we have a thimerosal video that you can watch and understand as well.