Nolan Alexander (Host): We're inching closer to that time of year, cold and flu season. Today, we'll discuss what's true and what's not with the flu vaccine with Dr. Casey Holloway Mabry. Dr. Mabry is a pediatrician and Internal Medicine physician at UM Baltimore Washington Medical Group in Glen Burnie. She provides comprehensive primary care to patients of all ages and is a working mother of three young children, so she's well aware of this topic.

Welcome to the Live Greater podcast series, information for a Healthier You from the University of Maryland Medical System. I'm Nolan Alexander. Dr. Mabry, so nice to have you here today. How are you?

Casey Holloway Mabry, MD: I'm doing well. Thanks so much for having me.

Host: Oh, it's our pleasure. I want to know why is the flu shot such an important tool for protecting both kids and adults every year?

Casey Holloway Mabry, MD: The flu shot is so important because the flu has the potential to be so dangerous. I think a lot of people don't really think about the flu as something potentially life-threatening. They think about it as just an annoyance of cold and flu season. But for children, for the elderly, for people who are immunocompromised, even for previously healthy adults, the flu can potentially be very, very dangerous, can be life-threatening. It can cause severe complications like strokes, heart attacks, lung infections, badness. And I think we have become a little desensitized to it because the flu vaccine has existed for a long time. But that doesn't make it any less important to get every year.

Host: Especially when you list off what could happen, and some people think, "I never get the flu, so I don't need the vaccine." I mean, do you respond to them with what could happen just like what you said?

Casey Holloway Mabry, MD: Well, I do. And also I like to remind people that vaccines are not only about preventing severe infection in the person who gets the vaccine, they're really important for preventing the spread of infection among a whole community. Last year was one of the worst flu seasons we've seen in the last 10 years. There were schools in 10 different states that had to shut down because of flu outbreaks. There were more hospitalizations from the flu last year than we saw in the last 10 years. There were over 260 deaths from pediatric patients. Children died last year because of the flu. So even if someone's not particularly concerned about themselves, getting the flu shot helps to protect those vulnerable people because it helps to limit the spread of infection in a whole community.

Host: So, how does that work? How do flu vaccines actually work to protect us and our communities?

Casey Holloway Mabry, MD: So, the flu vaccine, like all vaccines, introduces an inactivated version of a virus or a bacteria into your system to teach your immune system what to look out for. We're using your natural immune system to defend itself against this infection before it has a chance to make you sick. So, it's impossible for the flu shot to give you the flu. It's just like a calling card from the flu so that your body knows what to look out for this year so that it can attack any virus it comes into contact with in the real world and stop it from growing and spreading. So if the virus doesn't have anywhere to live, it can't spread in between people.

Host: So, that's a myth. You said the word impossible, because parents sometimes worry that the flu shot can give their child the flu.

Casey Holloway Mabry, MD: It is a huge myth that the flu shot can give you the flu. That's impossible. However, what sometimes gets confused for that is, one, anytime your immune system is activated, whether it's because you're getting sick or because you got a vaccine, you can have maybe 24 to 48 hours where you feel a little under the weather, right? You may have a low-grade fever, some muscle aches, some fatigue. That's just because your immune system is doing its job. So, that response to the vaccine is not a flu infection. That's one thing.

Another thing is once you get the flu shot, it takes about two weeks for your body to develop a full immunity based on that vaccine. And because we're giving the flu shot in cold and flu season, there's a chance that you come into contact with the flu virus before your vaccine has had a chance to really become effective. So, it's not so much the flu shot gave your child the flu, it's that maybe it didn't have an opportunity to actually protect them before they came into contact with the virus in the first place.

Host: That's very interesting, Dr. Mabry. Something else I've heard is, you know, "The flu shot, it doesn't work, so why bother?" What's the truth there?

Casey Holloway Mabry, MD: So, one reason that the flu shot in particular kind of has that myths surrounding it is because the flu virus itself changes every year. It mutates as it passes between people. So, we base our annual flu vaccine on whatever has happened with the flu virus in the southern hemisphere over our summer, right? It's their winter. So, we examine what's going on there. We design that year's flu shot based on the current flu virus that was there in the summer. And then, we make the vaccine for this fall. But there's a chance that the virus has changed in between the summer and the fall. So, sometimes the vaccine is not a 100% match to the virus that actually ends up spreading.

That doesn't mean that the flu shots useless. That doesn't mean that it's not helpful at all. You still get a good amount of protection, even if it's not a 100% match. But that's one reason that sometimes like, from year to year, it may be more or less effective. And that's another reason I really encourage everyone to get vaccinated because if we can prevent the spread of flu among people, we limit the opportunity for the virus to mutate, because it can only mutate as it passes from person to person. So if fewer people are getting sick, there's fewer mutations and the vaccine can stay more effective.

Host: That certainly makes sense. How do flu vaccines help protect the vulnerable groups, young children, older adults, or those with chronic illnesses?

Casey Holloway Mabry, MD: So, we know that young children, the elderly, and those with immune-compromising illnesses are all at the highest risk for complications from getting the flu. They're the ones at the highest risk to be hospitalized, to have severe bacterial infections as a result of the flu to potentially even die from the flu virus.

So, we want them especially to receive the flu vaccine to help protect them. But the same reasons that they're more susceptible to complications from the infection are also reasons why in them, as an individual, the flu vaccine may not be as effective. Their immune system is weak. So, they need the people around them with strong immune systems to get the flu vaccine, to prevent the spread of the flu virus among their community and to help them avoid coming into contact with it at all.

Especially in really young children, we don't start giving the flu vaccine until they're six months old. So for babies who were born in the summer through the winter, they may not even be old enough to get their flu vaccine and they need the adults and older children around them to be protected.

Host: You've touched a lot of the individual risk of skipping the flu shot. What about for the community?

Casey Holloway Mabry, MD: So as I was saying, one thing is to protect the vulnerable people in your community to help limit the spread of infection. I think that that's very important. But also, we have to consider things like loss of productivity, time off of work, children being out of school, schools having to shut down because of spread of flu. Like, we all remember how miserable it was to do school at home during COVID. We don't want to have to do that again because of the flu, when there's an effective vaccine every year. We just need people to get it.

Host: So if someone's listening to this and they're nervous about side effects, what should they know before getting vaccinated?

Casey Holloway Mabry, MD: As I was saying before, anytime you activate your immune system, there's a chance that you don't feel well. Sometimes there's a very, very rare chance that a severe side effect happens. One that I'm thinking of is something called Guillain-Barré, which is a really rare but serious nerve disease that can happen when your immune system is sort of overactivated. And that has been associated very, very rarely with the flu vaccine. About five cases for every million doses of vaccine given out. However, the chance of getting Guillain-Barré from the flu is higher than the chance of getting Guillain-Barré from the flu vaccine. Anytime the immune system is activated, there is a chance that something bad happens. But because the vaccines are an inactivated version of the virus, the risk of a serious complication is much lower from the vaccine compared to the actual infection.

And for the mild side effects like muscle aches, low-grade fever, fatigue, that can happen after the shot, you can totally take acetaminophen, ibuprofen, warm baths, hot showers. Take the day off. If you're worried about missing work, get the shot on a Friday afternoon. In about the next 24 hours, you should be feeling back to normal.

Host: Well, Dr. Mabry, you've done a fantastic job explaining things to us today. Is there anything else that you'd like to add?

Casey Holloway Mabry, MD: I just want everyone to know that the flu shots are safe, they are effective, and they are so, so important not only for protecting yourself, but also your loved ones and your whole community.

Host: Dr. Mabry, this was great. Thank you so much for your time today.

Casey Holloway Mabry, MD: Thank you so much for having me. This is really important to me.

Host: Find more shows just like this one at umms.org/podcast and on YouTube. Thank you for listening to Live Greater, a health and wellness podcast, brought to you by the University of Maryland Medical System. We look forward to you joining us again, and please share this on your social media.