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2 Types of Flu Vaccine

Distinguish between LAIV (live, weakened) and TIV (dead) vaccines, and when each is appropriate to be used. 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 Stanford School of Medicine.

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Video transcript

Voiceover: There are currently two kinds of influenza vaccines available. We have the flu shot and we have the nasal spray, also known as flu-mist. So, let's talk about some of the differences between these two kinds of vaccines. The most obvious difference between these two is the method of delivery. So, the flu shot is given as an intramuscular injection. This often occurs in the deltoid muscle and this happens because it's easily accessible and also there's a low risk of complication. However, the flu shot is also able to be given in the gluteus maximus, although in these modules we only teach the deltoid method. The flu shot can also be given as an intradermal injection, but again, we're only teaching the intramuscular injection in the deltoid. The nasal spray is, obviously, sprayed in the nose. So, that's the most obvious difference between the flu shot and the nasal spray. The most important difference is the condition of the virus used in each vaccine. So, the flu shot is sometimes called an inactivated vaccine. We call it inactivated because the virus that's used in this vaccine is effectively killed. It's not able to replicate inside of humans and as a result, there's no infection. The nasal spray is sometimes referred to as a live attenuated influenza vaccine. We use this word, attenuated, which means altered because the virus that's used in this vaccine is changed, although it's technically still alive. So, the changes or the alterations that occur in this virus, make it weaker, so in healthy people, their immune system is still able to defend against the virus and produce antibodies. In the future, if our vaccinated patient is exposed to a stronger version of the same virus, their immune system remembers how to defend against the virus and our patient is hopefully protected against infection. So, the reason why this difference is so important is because it determines who can get which kind of vaccine. So, can you get infected from the inactivated virus that's in the flu shot? Absolutely not. It's inactivated, it's not able to replicate and there's no infection. Can you get a full blown influenza illness from the live attenuated form? In most cases, the answer is likely not. Our immune systems are strong enough to defend against this weakened virus relatively easily, but there is some risk of getting a full blown influenza illness because this is still a live virus that's used in this vaccine. So, we have two groups of patients who should be vaccinated with the flu shot instead of the live attenuated form. So, those two groups are those who have an immune system that's not operating at 100%, they have weakened immunity. So, for these people, they have a greater likelyhood of getting sick from this attenuated virus than a normal healthy person would. The second group of people are patients who have a medical condition that places them at high risk of developing a complication from an influenza infection. So, these people get a much worse illness than a normal, healthy person would and as a result we really need to avoid any chance of infection whatsoever. So, given that we need to keep an eye out for these two groups of patients, let's talk about them in more detail starting with age group. So, because we require a fully developed and strong immune system in order to respond to the live attenuated virus, the nasal spray is only recommended for patients between the ages of 2 and 49 years of age. Outside of this age range, you are more likely to have a weaker immune system, so with the nasal spray is not recommended. However, there is no risk of infection with the flu shot because it uses a killed or inactivated virus. So, we can give the flu shot to anyone who is over the age of six months. Okay, so who else might have a weakened immune system? What about patients who have an immunodeficiency disease caused by HIV? Or patients who have had a medical procedure that leaves them immuno-suppressed. So, let's say a patient has an organ transplant and are taking medication that lowers their immunity on purpose. We call these patients immuno-suppressed. Pregnancy can also weaken the immune system and then people who have close contact with patients who are immuno-suppressed. We're also going to put them in this category because we want to make sure that they don't transmit the influenza virus to someone who has a weakened immune system. Okay, so these patients have even more reason to do everything they can to protect themselves from infection since their immune systems are weak, so we really want to get them vaccinated with the flu shot, which we know won't cause an infection. So, definitely vaccinate with the flu shot, but let's avoid the nasal spray in this situation. Okay, so now let's look more closely at this other group of patients. Those who have a high risk of developing complications from influenza. So, who might these people be? Well, any patient who has asthma. Patients who have problems with their heart or their kidney or any other pulmonary problems in addition to asthma. Patients who have diabetes. Now, there are also some other medical conditions that can lead to a high risk of complication with the flu, but these are the most common and most likely what you'll see in a vaccine clinic. So, for these patients, again, we absolutely should vaccinate them with the flu shot because we want to protect them from getting a bad illness, since their flu illness can lead to much more trouble than a normal, healthy person. So, absolutely give them the flu shot, but avoid the nasal spray here as well. Finally, let's talk about kids. There are a few circumstances that we need to look for in kids. Any child who has had a history of wheezing, even if they're not diagnosed with asthma should get the flu shot instead of a nasal spray. And then any kid or teenager, actually, who has been receiving aspirin, there's a complication known as Rye Syndrome that's associated with the aspirin and the influenza virus. So, we want to make sure that kids don't get the flu if they're taking aspirin. So, here again, definitely vaccinate with the flu shot, but no nasal spray. Okay, so now let's talk about patients who should consult their doctor before they get either vaccine, either the flu shot or the nasal spray. There are a few things to watch out for, so I like to use a mnemonic called FRAG to remember these patients. So, F stands for fever. Any patient actually with or without fever who has been sick in the last 24 hours, they should talk to their doctor before getting vaccinated. R stands for reaction. If your patient has received an influenza vaccine in the past and then had an emergency reaction as a result, they should also talk to their physician before getting vaccinated. A stands for allergy. The influenza vaccines are made in chicken eggs, so patients who are allergic to eggs or egg proteins should probably see an allergist before they get vaccinated. So, finally, G stands for Guillain-Barre'. This is a syndrome that I talked about in another module and basically all we need to know here is if your patient has received an influenza vaccine and then they developed Guillain-Barre' syndrome afterwards, they should consult a physician before getting vaccinated.