Resources

  1. Kwong JC et al. Acute Myocardial Infarction after Laboratory-Confirmed Influenza Infection. N Engl J Med. 2018 Jan 25;378(4):345-353


Transcript

Dr. Frank Domino:
As we know, it's been a really hard flu season. This is the worst season since the 2009 H1N1 pandemic. Still, many patients have yet to be vaccinated. And even among the elderly, the vaccination rate is only 65%. Hi, this is Frank Domino, Professor of Family Medicine and Community Health at the University of Massachusetts Medical School. And joining me today to discuss the influenza crisis and implications of our current flu season is Alan Ehrlich, Clinical Associate Professor in the Department of Family Medicine and Community Health, and Executive Editor at DynaMed. Thank you for coming, Alan.

Dr. Alan Ehrlich:
Thanks, Frank. 

Dr. Domino:
So, Alan, for those who still haven't, who should be getting the flu vaccine, and who is most at risk?

Dr. Ehrlich:
So, first of all, the vaccine is recommended for anyone six months of age or up, and so virtually everybody should be getting the vaccine. But there are particular groups that, really, as healthcare providers, we wanna make sure don't get missed. And those include, first of all, the elderly; pregnant women; anyone with chronic medical conditions, such as cardiovascular disease; respiratory conditions, such as asthma; metabolic conditions, like diabetes; any type of immunocompromised, whether it be from disease like HIV or from medication, such as being on chronic corticosteroids; residents of nursing homes or long-term care facilities; American Indians or Alaska natives; people who are morbidly obese; and anyone who either lives with or cares for any of the above groups are all considered high risk and should be targeted. And of course, healthcare professionals fit that last category.

Dr. Domino:
I think it should imply that all of us get one. But I agree, there are some high risk groups. I do worry the most about young children, infants in particular, and the elderly. Can you talk a little bit about the risks to the elderly?

Dr. Ehrlich:
Well, the risks to the elderly are that when they get influenza, they're more apt to get pneumonia and they have increased risks for other types of complications. One of the things that has been seen is the increased risk of cardiovascular disease in patients who are admitted for influenza.

Dr. Domino:

So tell me a little bit more about that. If you get the flu, you're at more risk for cardiovascular outcomes?

Dr. Ehrlich:
So actually there's a recent study that was published, looking at this. Some Canadian researchers looked to see, was there an increased risk after having diagnosed a episode of influenza for myocardial infarction. And so they searched a large database, found 20 patients who had had a myocardial infarction within seven days of having been diagnosed with influenza, by laboratory confirmation. And then, they looked at a large cohort to see what was the risk, going back one year earlier and one year later, from that point in time. So they looked at people who had influenza who, as the cohort, and so how many had myocardial infarctions within seven days. And then, looking back a year and forward a year, seeing what the risk was. And what they found was, the risk was in fact markedly elevated within one week. They actually looked at days 8 to 14, and found there was not a statistically increased risk at that point. So this was a primarily elderly population, and when they looked at those over 65 and those less than 65, this risk pertained to people who are over 65.

Dr. Domino:
Wow. So we normally think of the flu causing pulmonary disease or pulmonary adverse outcomes and death. But what you're saying is, if you're elderly and you get diagnosed with influenza, your chances of having a cardiac event go up within the first week after that diagnosis.

Dr. Ehrlich:
That's correct. And it didn't matter whether you had previously been diagnosed with a myocardial infarction or not.

Dr. Domino:
So this was just the entire general elderly population.

Dr. Ehrlich:
 
Yes. They also looked at some other infections, like RSV and adenovirus, and although some of those were associated with a slightly higher risk of myocardial infarction, none were as high as influenza.

Dr. Domino:
Wow. So that's really important, but it's late. It's February already. Is it too late to get the flu vaccine?

Dr. Ehrlich: 

No, it's not. The flu season continues well into April and even May. And in fact, those who have gotten immunized early in the season, if they are high risk, you might wanna consider giving them a booster later in the season, because immunity can wane.

Dr. Domino:
I have patients tell me all the time, A, the flu vaccine gives them the flu, or B, they've heard on the news that the vaccine's not that effective. Any thoughts on how we should respond to patients who give us this information?

Dr. Ehrlich: 

So let's take the first one. When patients tell me, "I got the flu after I had a flu shot," I always tell them or I'll ask them, "Well, tell me what happened." And usually what they mean is, they feel a little run down for a day or two. And I explain to them how feeling run down for a day or two is a whole lot different than getting the flu. And you're not getting hospitalized and you're not getting pneumonia from those types of symptoms. Those are just adverse effects. And if you are a high-risk individual, and any elderly patient would be in that category, they need to understand that their risk is much greater by not getting immunized. Even if they get the flu after being immunized, typically it will be less severe. Now, this year, there was a mismatch between the vaccine and the circulating strains, but we're never going to be perfect in that regard. And so the best hope for people is to get the immunization, and if you happen to get the flu anyhow, then come in and get treated with some medication if that's appropriate.

Dr. Domino: 
It's interesting, because when patients tell me, "Oh, I got ill after receiving the flu vaccine," I say, "That's wonderful. It shows that your body has an immune system and it's trying to build immunity to a variety of infections. Unfortunately, it wasn't the one that you received."

Dr. Ehrlich:
Well, certainly though, that is absolutely true in terms of trying to frame it in a way that's positive.

Dr. Domino:
I think it's important, with the severity of the flu epidemic this year, that we remind patients that it's worth getting immunized if they haven't been immunized. This key point about your increased risk of heart attacks and cardiovascular adverse outcomes is very, very important. Any final thoughts on influenza vaccine and the increased risks in the elderly, Alan?

Dr. Ehrlich:

I just think that this is just another opportunity to communicate with people about the importance of flu vaccine. And if this is just one more thing that'll convince somebody, who perhaps has a heart condition and has had a bad experience with the flu in the past, that they ought to get it. I will say, that for the people who say, "Well, I can't have it 'cause I have an egg allergy," there is a recombinant version that is safe for them.

Dr. Domino:
Thank you, Alan. I really appreciate you bringing this forward, and the reminder that it's not too late to get the flu vaccine, as well as the implications of not getting it can lead to an increased risk of adverse cardiac events in our elderly patients. Practice pointer: It's not too late to get the influenza vaccine. In this year of severe influenza, it's important that all patients over age six months of age be immunized. Join us next time when we talk about how to help patients feel empowered as they begin their treatment for depression, using a very simple communication tool called behavioral activation.