Article Archive
January/February 2022

Heart Disease & Flu: A Dangerous Combination
By Michele Deppe
Today’s Geriatric Medicine
Vol. 15 No. 1 P. 22

It’s not too late to educate your patients about the link between flu and heart disease and encourage them to get vaccinated.

“Get your flu shot” is a familiar community health campaign. Unfortunately, influenza and its related pneumonia are still among the top 10 causes of death in the United States.1 Other complications of the flu include bronchitis, lung failure, heart attack, and death. So avoiding the flu is certainly reason enough to get the vaccine. But there’s an additional incentive, according to a study published in the Journal of the American Heart Association: the influenza vaccination could significantly reduce the risk of a serious or fatal cardiac event in people with heart disease or associated risk factors.2

The Effects of the Flu on the Heart
Anyone who’s had the flu is aware of the common symptoms of aches, fever, and chills. The sneezing, stuffy nose, sore throat, and cough all point to respiratory discomfort. What do any of the common symptoms of the flu have to do with the heart? The same inflammation that drives up temperature and causes swelling, tenderness, and pain throughout the body adds stress to a heart, especially one that is already diseased. An article published by Harvard indicates that the pressure of inflammation is enough to dislodge the plaque inside vessels, resulting in a heart attack or stroke in some people.3 The inflammation response can also elevate blood pressure, increase the risk of blood clots, and result in swelling or scarring inside the heart. In addition to disease that’s already present, the heart may be taxed because flu has caused the lungs to be less efficient, lowering blood oxygen levels and demanding the heart work harder. Another strike against the heart is that the flu virus itself can attack cardiac muscle, leading to an event in an already weakened heart.4

Lifesaving Benefits of the Flu Shot for Cardiac Patients
A 2013 study published in JAMA reviewed pooled data from six clinical trials of more than 6,700 people.5 The median age was 67, and roughly one-third had heart disease. The study suggested that participants who had received the flu shot had a 36% lower risk of having a major cardiac event for the length of the vaccine life (a year). The flu vaccine’s protection is thought to be even more significant for people who have recently had a heart attack or stroke to lower their risk of suffering another event.

The Houston Methodist review published in the Journal of the American Heart Association reported that the flu vaccine effectively protects adults, making them 82% less likely to be admitted to the ICU for the flu and to have a 37% lower risk of being hospitalized at all.4 Among people hospitalized with the flu, vaccinated patients spent an average of four fewer days in the hospital than unvaccinated patients. Some patients admitted to the hospital with acute coronary syndrome (a range of conditions associated with sudden, reduced blood flow to the heart) were randomly chosen to receive a flu vaccine before discharge. When these cases were reviewed, the group that received a flu vaccination cut their risk of having a major cardiac event by half. The meta-analysis of many studies shows that the protective effects of the flu vaccine were similar to the standard interventions, including statin therapy, antihypertensive medication, and smoking cessation.

According to Joshua J. Joseph, MD, MPH, FAHA, “The flu vaccine helps your body create antibodies to the viruses that cause influenza. Those antibodies then work to protect your body from infection if they encounter the flu. While it’s possible to still get sick, studies show that having had the flu vaccine reduces the severity of the illness.”

There are different flu vaccinations formulated for older adults. The American Heart Association (AHA) states that a standard flu shot seems to be just as protective as a “high-dose” flu shot in people with heart disease. A high-dose flu shot includes four components or a shot with four components plus more antigens to aid the immune system; both are designed for those aged 65 and older. The Centers for Disease Control and Prevention (CDC) reports some studies show newer vaccines (the high-dose inactivated vaccine, the adjuvanted inactivated vaccine, and recombinant influenza vaccine) might be more effective than standard-dose inactivated vaccines without an adjuvant.6 However, at this time, older adults are advised that there is no preference for one vaccine over another unless a person’s physician deems otherwise.

Risk Is Especially Great This Year
This year, there is concern about the flu season coinciding with a pandemic. The AHA says that one-half of the patients hospitalized with the flu already have heart disease, increasing their risk of complications.1 The CDC reports that older adults make up the 70% to 85% of seasonal flu-related deaths.7 A 2020 cross-sectional study of 80,000 US adults hospitalized for flu (over eight flu seasons from 2010–2011 to 2017–2018) found that 1 in 8 patients experienced sudden, serious cardiac events.8 Of those, 31% were admitted to the ICU, and 7% died because of the event. The National Foundation for Infectious Diseases states that in older adults, flu increases the risk of a heart attack by three to five times and stroke by two to three times in the first two weeks following infection.9 In people older than age 65, this risk lingers for several months after influenza has passed.

The AHA states that older adults and people with underlying risk factors for chronic illness, including heart disease, stroke, and diabetes, should receive a flu vaccine, especially “those 50 years old and older.” According to the CDC, those with one or more chronic risk factors who aren’t vaccinated are six times more likely to experience a heart attack if they are also battling the flu.8

Additionally, there are now further complications. “This flu season is unusual because last season we had relatively low influenza activity due to the measures we were taking to prevent COVID-19, things like masking and social distancing,” Joseph says. “Now, those measures have relaxed. We also have lower population immunity because of the low virus activity. Everyone getting their flu shot is an essential way we can keep the flu from spreading and claiming lives.” Joseph says the goal is to prevent a “twin-demic,” which refers to having high numbers of COVID-19 cases and influenza cases circulating at the same time. “It’s very important to keep this from happening,” he says, “so our health care systems can serve us best.”

There are tests to check for the presence of flu and COVID-19. Flu vaccination should be delayed for people who have a suspected or confirmed case of COVID-19. Those individuals can then receive the flu shot when they are no longer acutely ill or as advised by their doctor. In those without symptoms, the flu vaccination and COVID-19 vaccine may be given simultaneously.10

Sociodemographic Reasons Why People Don’t Get Flu Vaccination
In a National Health Interview Survey that reviewed data from 2008 to 2016, the vaccination rate was 76% among people aged 65 and older who had a history of cardiovascular disease.11 In other studies, older Black and Hispanic adults with cardiovascular disease were less likely to get flu shots than were other groups.12 Older adults who live with family members are more likely to receive vaccination than are people who are divorced or widowed. Lower income, lower levels of completed education, having fewer doctor’s visits, or exposure to health care are also considerable barriers to getting a flu shot.

Perception plays a part. In a Canadian Community Health Survey, people who judged their health as being poor were 21/2 times more likely to get a flu shot than were individuals who believed themselves to be in good health.13

Motivating health care staff about flu shots is vital as workers are already inundated by the pandemic. According to a 2007 study published in the British Journal of General Practice, the best motivation for older adults to get the flu shot is education and recommendation by health care professionals.14 Recent research confirms that providers can improve vaccine uptake through education. Providing patients with ideas about where to get safe, local access to flu shots is helpful if you cannot provide vaccination directly. Community outreach is effective, such as having a doctor, nurse, or other health care professional visit a senior center. Postcards, emails, ads on social media, and coupons for free vaccination are some ways to encourage older adults to get a flu shot. An article in the American Journal of Medicine suggested generating best-practice alerts in the chart to cue health care workers to remind patients to get vaccinated.15 Standing orders from the attending physician allow nurses, pharmacists, and other health care personnel to give flu shots to older patients who haven’t had them. Thus, they make the most of opportunities where patients may otherwise go unvaccinated.

Flu Represents an Ever-Changing Environment
Numerous studies since 2010 prove that flu vaccines help protect against influenza A (H1N1) or influenza B viruses by more than 60% among people 65 years and older, reducing both the need for doctor’s visits and hospitalizations. However, with some other vaccines that have not been as effective against other types of flu, the benefit falls to around 40%.16

However, since each season changes, it’s challenging to know which vaccine will always be effective in each season, so public health experts continue to gather data about newer vaccines and their effectiveness. Providers may consider recommending new vaccines as research becomes available. The CDC updates the information regularly beginning in mid-October at their “Weekly Flu Vaccination Dashboard.”

Health organizations around the globe encourage flu vaccination for people who live in the same household as older people and promote vaccination for caregivers and health care workers.15

Older adults with confirmed heart disease or associated risk factors can benefit significantly from getting influenza vaccination. Each year, there are 12,000 to 61,000 deaths in the United States from influenza, and 1 in 8 patients admitted with the flu has an acute cardiovascular event.17 The ongoing COVID-19 health crisis makes it even more critical to prevent a concurrent epidemic and lessen the load on an already overwhelmed health care system. Physicians, nurses, therapists, and other geriatricians represents one of the most effective means to getting older adults vaccinated, as they often can recommend flu shots during care.

A flu shot is not 100% effective, but may lessen the severity of illness. Although the pandemic has caused many to form new habits, older people should continue daily preventive habits as their first defense against the flu. For example, the CDC recommends that people stay home when they don’t feel well, wash hands often and wipe down surfaces, cover coughs and sneezes, practice good self-care (adequate rest, good diet, manage stress), and avoid close contact with people who are sick.

— Michele Deppe is a freelance writer based in South Carolina.


1. Despite risks, 60% of Americans say they may delay or skip flu shot this year. American Heart Association website. Published October 12, 2021. Accessed November 17, 2021.

2. Yedlapati S, Khan S, Talluri S, et al. Effects of influenza vaccine on mortality and cardiovascular outcomes in patients with cardiovascular disease: a systematic review and meta-analysis. JAHA. 2021;10:e019636.

3. Flu shot linked to lower heart attack, stroke risk. Harvard Health Publishing website. Published October 23, 2013. Accessed November 17, 2021.

4. McCleskey E. Flu and heart disease: the surprising connection that should convince you to schedule your shot. Houston Methodist On Health Blog website. Published October 8, 2021. Accessed November 17, 2021.

5. Udell J, Zawi R, Bhatt D, et al. Association between influenza vaccination and cardiovascular outcomes in high-risk patients: a meta-analysis. JAMA. 2013;310(16):1711-1720.

6. Fluzone high-dose seasonal influenza vaccine. Centers for Disease Control and Prevention website. Updated August 27, 2021. Accessed November 17, 2021.

7. Flu & people 65 years and older. Centers for Disease Control and Prevention website. Updated August 26, 2021. Accessed November 17, 2021.

8. Flu & people with heart disease and stroke. Centers for Disease Control and Prevention website. Updated August 26, 2021. Accessed November 17, 2021.

9. Influenza and older adults. National Foundation for Infectious Disease website. Accessed November 17, 2021.

10. In light of pandemic, flu vaccinations more important than ever for people at highest risk. American Heart Association website. Published November 9, 2020. Accessed November 17, 2021.

11. Estimates of influenza vaccination coverage among adults – United States, 2017-18 flu season. Centers for Disease Control and Prevention website. Updated November 5, 2018. Accessed November 17, 2021.

12. Flu disparities among racial and ethnic minority groups. Centers for Disease Control and Prevention website. Updated November 9, 2021. Accessed November 17, 2021.

13. Gutherie J, Fisman D, Gardy J. Self-rated health and reasons for non-vaccination against seasonal influenza in Canadian adults with asthma. PLos One. 2017;12(2):e)172117.

14. Evans M, Prout H, Prior, Tapper-Jones L, Butler C. A qualitative study of lay beliefs about influenza immunization in older people. Br J Gen Pract. 2007;57(538):352-358.

15. Bhugra P, Grandhi G, Mszar R, et al. Determinants of influenza vaccine uptake in patients with cardiovascular disease and strategies for improvement. JAHA. 2021;10:3019671.

16. Vaccine effectiveness: how well do flu vaccines work? Centers for Disease Control and Prevention website. Reviewed October 25, 2021. Accessed November 17, 2021.

17. How the CDC estimates the burden of seasonal influenza in the U.S. Centers for Disease Control and Prevention website. Reviewed November 22, 2019. Accessed November 17, 2021.

In an online survey of 1,000 US adults, participants answered at least one of eight questions to demonstrate knowledge about the flu shot.1 The majority (94% of those surveyed) answered at least one question incorrectly. As the oldest group surveyed at ages 57 to 75, Baby Boomers were a little more accurate (58% answered one question incorrectly). In an American Heart Association press release, Lloyd-Jones states that simple patient education is an effective way to get more older adults vaccinated. An article from Houston Methodist Hospital suggests that patients with heart disease tend to visit their cardiologists more often than they do their primary care physicians, and cardiology offices may not offer vaccines.2 Your interaction with the patient may be the only reminder that they receive to get the flu shot.

Here’s a quick refresher to share with your geriatric patients about flu shots:

Timing. Getting vaccinated late is better than not at all. Ideally, adults 65 years and older should get a flu shot before the end of October. However, most older adults should not get vaccinated early (in the summer). Earlier vaccination isn’t recommended because the antibody response to the flu vaccine begins to decline over time. However, getting vaccinated later in the flu season, which ends in May, is always better than no flu shot. According to the Mayo Clinic, the flu shot takes about two weeks to reach its full effectiveness.3

Side Effects. Side effects from getting a flu vaccination are usually limited to soreness, swelling, or redness at the injection site. The vaccine does not cause the flu. According to the Centers for Disease Control and Prevention, flu shots have a long, established safety record.

Easy Access. Encourage older adults to seek the flu vaccine where they usually get their prescriptions filled. Doctors and some employers can provide vaccines as well. In addition, some facilities such as community health centers, churches, and federally funded programs offer the vaccine for free to older adults. Remind patients to wear a mask while being vaccinated this year.

Who Shouldn’t Get a Flu Shot? People with serious allergies, including those who have had a severe allergic reaction to flu shots in the past and those with a history of Guillain-Barré Syndrome, should not get the flu shot. Some people receive a nasal spray flu vaccine, but this is generally not recommended for people older than 49.4

Know the Difference. Although symptoms may be similar, according to the Centers for Disease Control and Prevention, we are not currently experiencing an influenza virus pandemic; there is only an ongoing pandemic with a “new” coronavirus. An influenza pandemic is a global outbreak of a new influenza A virus that is very different from the current and recently circulating flu viruses. Therefore, some patients should be informed that we’re vaccinating to prevent rising flu numbers during this time and that flu vaccines are altered every year to respond to prevalent viruses.5


1. Despite risks, 60% of Americans say they may delay or skip flu shot this year. American Heart Association website. Published October 12, 2021. Accessed November 17, 2021.

2. McCleskey, Eden. Flu and heart disease: the surprising connection that should convince you to schedule your shot. Houston Methodist On Health Blog website. Published October 8, 2021. Accessed November 17, 2021.

3. Flu shot: your best bet for avoiding influenza. Mayo Clinic website. Published September 10, 2021. Accessed November 17, 2021.

4. Who should and who should not get a flu vaccine. Centers for Disease Control and Prevention website. Published August 24, 2021. Accessed November 17, 2021.

5. How is pandemic flu different from seasonal flu? Centers for Disease Control and Prevention website. Updated May 7, 2019. Accessed November 17, 2021.