Flu Shot Might Have Protected Some People From Severe COVID

Man standing by flu shot sign.

Noam Galai / Contributor

Key Takeaways

  • Research has found people who got the flu shot were 20% less likely to be admitted to the intensive care unit with COVID-19.
  • People who received their annual flu shot also had a lower risk of serious complications from COVID-19 like sepsis and stroke.
  • It's unclear why the flu shot may have a protective effect, or if it does at all.

Every year, getting your annual flu shot is crucial. But as COVID-19 continues to circulate it may be more important than ever. New research reports that the seasonal flu shot may have protected some people from developing severe cases of COVID-19.

The study, which was presented ahead of publication at the European Congress of Clinical Microbiology & Infectious Diseases, analyzed de-identified electronic patient health records. According to a press release, the researchers looked at data from two groups of 37,377 patients from countries across the world, including the U.S., U.K., Germany, Italy, Israel, and Singapore.

The first group had received the flu vaccine between two and six months before they were diagnosed with COVID-19. Patients in the second group also contracted COVID-19 but were not vaccinated against the flu.

Both groups were matched for factors that could impact their risk of severe COVID-19, like age, ethnicity, smoking habits, and underlying health problems.

The researchers found that those who did not have the flu vaccine were up to 20% more likely to have been admitted to the intensive care unit than those who got their annual shot.

People who didn’t have their flu shot were up to 58% more likely to visit the emergency room and up to 45% more likely to get sepsis. They were 58% more likely to have a stroke and 40% more likely to have a deep vein thrombosis. However, the risk of death was similar, whether a patient had the flu shot or not.

Senior study author Devinder Singh, MD, professor of clinical surgery at the University of Miami Miller School of Medicine, tells Verywell that his work suggests “a potential protective effect” that could be helpful for people in areas that don’t have easy access to COVID-19 vaccines.

What This Means For You

Getting your annual flu shot may help lower your risk of severe COVID-19. However, experts stress that the best way to protect yourself from severe COVID-19 is to get the COVID-19 vaccine. You can find an appointment here.

Why Might the Flu Shot Protect Against Severe COVID?

This isn’t the first study to find a link between people who received the flu shot and a lowered risk of severe complications from COVID-19.

A study of 27,201 patients who were tested for COVID-19 that was published in the American Journal of Infection Control in June found that patients who received the flu shot had a 24% less chance of testing positive for the virus than those who did not get their flu shot.

Another study published in January in the Journal of the American Board of Family Medicine of more than 2,000 patients found that COVID-19 patients who didn’t get a flu shot in the last year had a nearly 2.5 greater chance of being hospitalized with COVID-19 and more than three times greater risk of ICU admission compared to their vaccinated counterparts.

But it’s not entirely clear why the flu shot may help.

"The mechanism may have to do with priming the innate immune system to help recognize future viral infections,” Richard Watkins, MD, an infectious disease physician and professor of internal medicine at the Northeast Ohio Medical University, tells Verywell.

But Watkins says that it may simply be that people who tend to get vaccinated against the flu are also more likely to engage in things that would reduce their risk of severe COVID-19. “They may be more diligent about taking precautions such as social distancing, getting the COVID-19 vaccine, and wearing a mask,” he says.

Still, Singh says, the “flu vaccine has a much longer track record of safety, and this fact may help address the hesitancy reported in some people with respect to the COVID-19 vaccine.”

Singh stresses that it’s “very important” to note that the researchers “absolutely recommend the COVID-19 vaccine,” adding that they aren’t suggesting that people use the flu shot to prevent COVID-19 in place of the COVID-19 vaccine.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Conlon A, Ashur C, Washer L, Eagle KA, Hofmann Bowman MA. Impact of the Influenza Vaccine on COVID-19 Infection Rates and Severity. American Journal of Infection Control. June 2021. doi: S0196-6553(21)00089-4.

  2.  Yang M-J, Rooks BJ, Thi Le T-T, et al. Influenza Vaccination and Hospitalizations Among COVID-19 Infected Adults. Journal of the American Board of Family Medicine. January 25, 2021.