Tip/Thought of the Day

Studies Show the Flu Vaccine Protects Against Severe Covid-19

A study released early August 2021 revealed that patients who received an influenza vaccine were found to have 24% lower odds of testing positive for COVID-19. The study, published in the American Journal of Infection Control also revealed that patients that received their flu shots and tested positive for Covid-19 were found to have better outcomes than their counterparts that had not received their flu shot. This is significant news as we enter yet another flu season as Covid-19 cases continue to run rampant in our country.

The large-scale study included patient data of people from several countries, including Germany, Israel, Italy, Singapore, and the U.K. Using the TriNetX research database, researchers sifted through de-identified health records for more than 70 million patients, ending up with two groups of 37,377 patients. The two groups were then matched for factors that could influence their risk of susceptibility to severe COVID-19, including but not limited to age, gender, ethnicity, smoking, and health problems such as diabetes, obesity, and chronic obstructive pulmonary disease.

Members of the first study group had received the flu vaccine 6.5 months prior to being diagnosed with COVID-19. Those in the second group also had a positive COVID-19 diagnosis but were not vaccinated against the flu. Researchers explained that the incidence of 15 adverse outcomes were then compared between the groups. All these factors were documented within periods of 30, 60, 90 and 120 days of testing positive for COVID-19. The adverse outcomes included:

  • sepsis
  • strokes
  • deep vein thrombosis (DVT)
  • pulmonary embolism
  • acute respiratory failure
  • acute respiratory distress syndrome
  • arthralgia or joint pain
  • renal failure; anorexia
  • heart attack
  • pneumonia
  • emergency department visits
  • hospital admission
  • ICU admission
  • death

The analysis revealed that those who had not received the flu shot were significantly more likely (up to 20% more likely) to have been admitted to the ICU. They were also significantly more likely to visit the emergency department (up to 58% more likely), to develop sepsis (up to 45% more likely), to have a stroke (up to 58% more likely) and a DVT (up to 40% more likely). The risk of death was not reduced.

The exact reason behind the improved outcomes and protection against Covid-19 isn’t yet fully understood. Researchers theorize that the flu shot may boost the immune system.

However, the investigators noted that there is a “hypothetical, yet plausible immunologic mechanism” associated with flu shots that could result in trained immunity, where a vaccine results in an adaptive immune response that can be activated in response to a nonspecific antigen, such as how a tuberculosis vaccine has shown to be effective against yellow fever and malaria.

“Even if the direct link between the prevention of COVID-19 and the influenza vaccine is minimal, through an overall reduction in the number of patients presenting to their providers with viral-like symptoms necessitating work up for COVID-19 or requiring hospitalization for complications of influenza, vaccination will preserve health care resources for those with COVID-19,” wrote the researchers.

What are the benefits of the flu vaccine?

Influenza is a serious disease that can lead to hospitalization and sometimes even death. During flu season, flu viruses circulate at higher levels in the U.S. population. “Flu season” in the United States can begin as early as October and last as late as May.

An annual seasonal flu vaccine is the best way to reduce your risk of getting sick and spreading it to others. Every year, experts recommend that anyone 6 months of age or older get a flu shot, unless they have a severe, life-threatening allergy to the vaccine. It takes 2 weeks before the vaccine becomes effective so illness can still occur during that time. That’s why it’s imperative to get it early in the fall before flu season takes hold.

Every flu season is different, and the influenza infection can affect people differently. Millions of people get the flu every year, hundreds of thousands of people are hospitalized, and tens of thousands of people die from flu-related causes every year. Even healthy people can get very sick from the flu and spread it to others. The CDC estimates that flu-related hospitalizations since 2010 ranged from 140,000 to 710,000, while flu-related deaths are estimated to have ranged from 12,000 to 56,000. Of those who died, 80% were not vaccinated and 40% of children had no risk factors for complications. When more people get vaccinated against the flu, less flu can spread through that community. 

A flu vaccine is needed every season for two reasons. First, the body’s immune response from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, the formulation of the flu vaccine is reviewed each year and sometimes updated to keep up with changing flu viruses. There is still a possibility you could get the flu even if you got vaccinated. The ability of the flu vaccine to protect a person depends on various factors, including the age and health status of the person being vaccinated, and also the similarity or “match” between the viruses used to make the vaccine and those circulating in the community. If the viruses in the vaccine and the influenza viruses circulating in the community are closely matched, vaccine effectiveness is higher. If they are not closely matched, vaccine effectiveness can be reduced.

However, it’s important to remember that even when the viruses are not closely matched, the vaccine can still protect many people and prevent flu- related complications. Such protection is possible because antibodies made in response to the vaccine can provide some protection (called cross-protection) against different, but related, influenza viruses.

This year (again), flu vaccines are crucial

This year our country is again being overrun by Covid-19, largely impacting those that have not received their Covid-19 vaccine. Medical facilities and providers are overwhelmed by the amount of cases. In addition to getting your Covid-19 vaccine (click here to find and register for a vaccine in AZ), getting a flu shot is essential this season. Susan Taghioff, co-lead author of the study surrounding the protection the flu shot provides against Covid-19, said, “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.”

Cross-protection is vital this year, as “Every time you get a virus it can predispose you to having another infection on top of it,” said Flor M. Muñoz, M.D., a pediatric infectious disease specialist at Texas Children’s Hospital in Houston and the lead author of the American Academy of Pediatrics’ recommendations for preventing influenza. Providers are also working to educate people on the importance of the flu shot this year as an influx of flu cases could lead to what people last year called a “Twindemic”, with the American health care system juggling both a heavy flu season and COVID-19.

Medical providers are counting on the general population to help ease the load of patients in hospitals by maintaining their health and taking preventative measures to avoid requiring medical care. Do not put off routine wellness visits, follow-up appointments, etc. Speak to your provider about what is best in your situation; maintaining your health is an essential factor in keeping you and your loved ones healthy and safe as well as assisting those caring for patients with COVID-19 related illness.

Courtney Medical Group has remained open so that our patients can continue to receive the highest standard of medical care under the most stringent safety guidelines. When necessary we can also “see” you telemedically. Maintaining your health is the key to staying healthy throughout these tough times. We expect flu vaccines will be available August 23rd, 2021. Please contact us if you would like to schedule an appointment to receive yours.














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