MIAMI, Fla. — Still hesitant to get the COVID-19 vaccine? How about settling for a flu shot instead? A new study reveals the annual influenza vaccine may provide significant protection against some of the most serious complications from a coronavirus infection.
Researchers from the University of Miami Miller School of Medicine say the largest study of its kind to date has discovered that the basic flu shot lowers the risk of stroke, sepsis, and blood clots in patients with COVID-19. Moreover, COVID patients who have been vaccinated against the flu are also less likely to need hospitalization or enter the intensive care unit.
Study authors note their findings are particularly important since much of the world is still waiting to receive their COVID vaccinations. Hesitancy due to distrust of vaccines or unfounded claims about side-effects have also kept countries from reaching their goals for herd immunity.
“Only a small fraction of the world has been fully vaccinated against COVID-19 to date, and with all the devastation that has occurred due to the pandemic, the global community still needs to find solutions to reduce morbidity and mortality,” says senior study author Devinder Singh, M.D., chief of plastic surgery and professor of clinical surgery at the Miller School, in a university release.
“Having access to the real-time data of millions of patients is an incredibly powerful research tool,” adds Dr. Singh. “Together with asking important questions, my team has been able to observe an association between the flu vaccine and reduced morbidity in COVID-19 patients.”
A flu shot may keep COVID patients out of the hospital
Researchers examined the electronic health records from a database of more than 70 million anonymous patients in the U.S., United Kingdom, Germany, Italy, Israel, and Singapore. From that pool, the team selected nearly 75,000 patients, which they split into two equal groups.
The first group of 37,377 COVID patients received a flu shot between two weeks and six months prior to their diagnosis. The second group tested positive for the virus but did not receive an annual flu vaccine. The team compared these groups, looking at rates of 15 severe complications due to coronavirus within 30, 60, 90, and 120 days of infection.
Those conditions included sepsis, strokes, deep vein thrombosis or DVT blood clots, pulmonary embolism (a blood clot in the lungs), acute respiratory failure, acute respiratory distress syndrome (ARDS), joint pain, kidney failure, anorexia, heart attack, pneumonia, emergency room visits, hospital admission, ICU admission, and death.
In comparison to patients getting their flu shots, unvaccinated COVID patients were up to 20 percent more likely to enter a hospital ICU due to coronavirus. People who did not get a flu shot were nearly 60 percent more likely to need hospitalization and 45 percent more likely to develop sepsis. They were also 58 percent more likely to suffer a stroke and up to 40 percent more likely to develop DVT blood clots while dealing with COVID-19.
Study authors note the risk of death did not noticeably decrease among patients getting their annual flu vaccine.
A flu shot is not a substitute for the COVID vaccine
The Miami team says it’s unclear what exactly makes a flu shot so protective for COVID patients. However, the team theorizes that the influenza vaccine boosts the body’s innate immune system — strengthening the defenses that protect against all forms of illness.
Despite these findings, researchers say opting for a flu shot this fall is no substitute for the coronavirus vaccine. They urge people to receive both shots in order to avoid both the coronavirus and a potential resurgence of the flu after public safety measures end.
“Continued promotion of the influenza vaccine also has the potential help the global population avoid a possible ‘twindemic’ — a simultaneous outbreak of both influenza and coronavirus,” concludes lead author and medical student Susan Taghioff. “Regardless of the degree of protection afforded by the influenza vaccine against adverse outcomes associated with COVID-19, simply being able to conserve global health care resources by keeping the number of influenza cases under control is reason enough to champion continued efforts to promote influenza vaccination worldwide.”
The findings appear in the journal PLOS ONE.