Feature | Coronavirus (COVID-19) | February 23, 2021 | By William Schaffner, M.D., and Allen J. Taylor, M.D.

Cardiologists Should Prioritize Influenza Vaccination Amidst COVID-19 Pandemic

Influenza vaccination essential to managing heart disease and reducing strain on U.S. healthcare resources 

Vaccinating patients against the flu can go a long way to helping cardiology patients stay healthy and out of the hospital during the COVID-19 pandemic, freeing up beds for COVID patients. Left photo, Getty Images, right image of COVID-19 virus from the NIH.

Vaccinating patients against the flu can go a long way to helping cardiology patients stay healthy and out of the hospital during the COVID-19 pandemic, freeing up beds for COVID patients. Left photo, Getty Images, right image of COVID-19 virus from the NIH.

While influenza (flu) is unpredictable, the 2020-2021 influenza season may present an unprecedented dual threat: co-circulation of influenza and the novel coronavirus (SARS-CoV-2) that causes COVID-19, and the resulting increased burden on the U.S. healthcare system. As people increasingly congregate indoors during inclement winter weather, there is growing concern that the co-circulating respiratory viruses could culminate in an even larger public health crisis — particularly for the 150 million adults living with heart disease and other chronic health conditions. 

Both SARS-CoV-2 and influenza are contagious viruses, causing similar symptoms, inflammatory reactions and related complications. Both infections are particularly dangerous for individuals with chronic health conditions, including heart disease, diabetes and lung disease, such as asthma and chronic obstructive pulmonary disease (COPD). 


Heart Disease Increases Risks of Flu Complications

Each year in the U.S., influenza is responsible for millions of illnesses, hundreds of thousands of hospitalizations, and tens of thousands of deaths. Patients with heart disease face an increased risk for serious influenza-related complications. During the 2019-2020 influenza season, 92.6 percent of patients hospitalized for influenza complications had at least one underlying chronic health condition.[1] The most common (47 percent) was heart disease, which affects more than 30 million U.S. adults.[2] For weeks after the initial infection has passed, influenza can cause an inflammatory reaction that can aggravate underlying conditions, potentially leading to heart attack, stroke, or catastrophic disability.

Alarmingly, the risk of having a heart attack is six times greater within a week of a lab-confirmed influenza infection, compared to a year before or after infection.[3]

While we are still learning about the mechanisms of COVID-19 infection and its interaction with influenza, patients with pre-existing cardiovascular disease and diabetes have been especially vulnerable to serious illness and post-infection damage to heart tissue. Like influenza, hospitalizations and deaths due to heart disease peak in the winter months. Adding COVID-19 to the mix creates a triple threat.


Flu Shots Are Available and Can Keep People Out of the Hospital During COVID Surges

Due to surges in the number of COVID-19 cases, U.S. emergency rooms are already overloaded, without the additional strain caused by influenza. Experts warn of the daunting prospect of treating both influenza and COVID-19 patients competing for the same resources, including intensive care unit (ICU) beds and personal protective equipment. As the dual threat of influenza and COVID-19 looms during the winter months, managing ICU strain will remain a challenge. 

While we do have safe and effective vaccines available to mitigate the worst outcomes associated with influenza, estimates show that only 52 percent of individuals in the U.S. age six months and older received an influenza vaccine during the 2019-2020 season. That is simply not good enough, especially this season, during a global pandemic. A call to action by the National Foundation for Infectious Diseases (NFID), "The Dangers of Influenza and COVID-19 in Adults With Chronic Health Conditions," represents a rallying cry for healthcare professionals to prioritize annual influenza vaccination in vulnerable populations, and offers specific implementation strategies.[4] 

Influenza vaccination has been shown to reduce serious influenza-related complications, including hospitalization. During the 2019-2020 influenza season alone, influenza vaccination prevented an estimated 7.5 million illnesses, 105,000 hospitalizations, and 6,300 influenza deaths. By prioritizing influenza vaccination, particularly among adults with chronic health conditions who are most likely to be hospitalized, health systems will be able to reserve critical staff, resources, and space in hospitals, to allow for better management of COVID-19 illnesses.

Despite the evidence that influenza vaccination can prevent or mitigate serious influenza outcomes, rates remain suboptimal across all groups, including high-risk populations. A recent NFID survey found that nearly a quarter of U.S. adults at high risk for influenza-related complications did not plan to get vaccinated during the 2020-2021 influenza season,[5] and according to the Centers for Disease Control and Prevention, fewer than half of adults age 50-64 years regularly receive annual influenza vaccination. 

Healthcare professionals face the unique challenge of improving influenza immunization rates during a global pandemic which has caused many to shelter in place and neglect or delay routine healthcare, including vaccinations. Case in point: Immunization rates for all adult vaccines dropped 12 percent to 63 percent compared to this time last year, varying by state, and nearly half of adults age 50 years and older are not up to date with recommended vaccines.[6] 

There is an urgent need for cardiologists and other healthcare professionals to actively engage with patients and urge them to prioritize vaccination. Those at greatest risk for serious complications or death from COVID-19 are often the same as those at greatest risk from influenza. As healthcare professionals, we are among the most trusted source of medical information for patients and their caregivers and families. We must all work together to make strong recommendations for annual influenza vaccination. 
The NFID Call to Action, available online at nfid.org/loweryourflurisk, offers proven strategies and resources to help approach this challenge. We need to engage community groups and trusted local leaders, particularly those in at-risk and underserved communities. Healthcare professionals should also regularly talk about the importance of annual influenza vaccines (and where to get one), with messages on how to be vaccinated safely (wearing masks and keeping social distances), and why it is especially important to be vaccinated against influenza during the COVID-19 pandemic. Social media, community health advocates, and peer influencers can and should be rallied to help spread the word and dispel misinformation.


Flu Vaccine Should be Part of Routine Cardiac Patient Care

Annual influenza vaccination should be part of routine care for heart disease patients. A growing body of evidence suggests that influenza vaccination can prevent both heart attack and stroke and efficacy estimates range from 15 to 45 percent, similar to the efficacy of statins, antihypertensive therapy, and smoking cessation.[7] 

While many cardiology practices may not stock influenza vaccines, during each patient encounter, even phone or virtual telehealth interactions, cardiologists must insist that patients receive an annual influenza vaccine. Cardiologists should refer patients to a nearby pharmacy or other convenient location that provides flu vaccines. Additionally, giving patients a “prescription” for flu vaccination is an effective strategy used by specialists to emphasize the importance of flu vaccination. 

Due to the COVID-19 pandemic, healthcare professionals and hospital systems have been stressed to an unprecedented degree. While the science is progressing, much remains unknown about COVID-19, making it all the more important that we use the tools we readily have available, including annual influenza vaccination, to reduce disease burden among patients with cardiovascular disease and other chronic health conditions. 


Related COVID Vaccine Content:

FDA Clears Third COVID-19 Vaccine From Janssen

FDA Clears First COVID-19 Vaccine Under an Emergency Use Authorization

FDA Approved Second COVID-19 Vaccine From Moderna

COVID-19 Patients With Cardiovascular Disease Have In-hospital Mortality Rates of 25 to 38 Percent

Who Qualifies for the COVID Vaccine Under CDC Guidelines

Cardiology related COVID news and video


About the authors: William Schaffner, M.D., is medical director of the National Foundation for Infectious Diseases (NFID) and professor of preventive medicine and infectious diseases at Vanderbilt University School of Medicine in Nashville, Tennessee. Schaffner is a past-president of NFID and is active in the field of infectious disease research and has authored or co-authored more than 400 published studies, reviews, and book chapters on infectious diseases. 

Allen J. Taylor, M.D., is chair of cardiology, MedStar Heart and Vascular Institute, MedStar Washington Hospital Center and MedStar Georgetown University Hospital.



1. CDC. What are the benefits of flu vaccination? Published August 31, 2020. www.cdc.gov/flu/prevent/vaccine-benefits.htm. Accessed September 21, 2020.

2. CDC. Preliminary In-Season 2019-2020 Flu Burden Estimates. Centers for Disease Control and Prevention. Published April 17, 2020. www. cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm. Accessed August 25, 2020.

3. Kwong JC, Schwartz KL, Campitelli MA, et al. Acute Myocardial Infarction after Laboratory-Confirmed Influenza Infection. New England Journal of Medicine. 2018;378(4):345-353. doi:10.1056/ NEJMoa1702090.

4. The Dangers of Influenza and COVID-19 in Adults with Chronic Health Conditions. National Foundation for Infectious Diseases. Posted online October 15, 2020. Accessed Feb. 23, 2021. https://www.nfid.org/2020/10/15/the-dangers-of-influenza-and-covid-19-in-adults-with-chronic-health-conditions/.

5. National Survey: Attitudes about Influenza, Pneumococcal Disease, and COVID-19. National Foundation for Infectious Diseases. https://www.nfid.org/wp-content/uploads/2020/10/NFID-Call-to-Action-Dangers-of-Influenza-and-COVID-19-in-Adults-with-Chronic-Health-Conditions.pdf

6. Vaccine Rates for All Ages Drop Dramatically During COVID-19. Medscape. www.medscape.com/viewarticle/931913. Accessed August 28, 2020.

7. MacIntyre CR, Mahimbo A, Moa AM, Barnes M. Influenza vaccine as a coronary intervention for prevention of myocardial infarction. Heart. 2016;102(24):1953-1956. doi:10.1136/heartjnl-2016-309983.

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