According to a recent study, the flu vaccine does not increase a person’s risk of getting COVID-19 and is not associated with severe illness and death from the disease.

Doctor placing Bandaid over vaccination site
This year, the flu vaccine is more important than ever.

The research, which features in the Journal of Clinical and Translational Science, reveals that the flu vaccine is the single most important way to protect people’s health this fall and winter.

Seasonal flu activity can be unpredictable, and it is common for otherwise healthy people to be hospitalized due to critical respiratory infection each year.

Statistics from the Centers for Disease Control and Prevention (CDC) show that during the 2019-2020 United States flu season, there were 39–56 million cases of the disease. There were also 18–26 million flu medical visits, requiring up to 740,000 hospitalizations. Furthermore, flu may have caused the deaths of as many as 62,000 people in the U.S.

Preventing a ‘twindemic’

Studies investigating the 1918 flu pandemic suggest that a second wave of COVID-19 is possible in the fall and winter of 2020. This would overlap with seasonal flu’s most active phase.

Preventive measures, such as physical distancing, have also reduced the spread of the flu. The CDC reported that positive test results dropped from more than 20% to 2.3% during the pandemic and have remained at “historically low interseasonal levels.”

As the flu season merges with the COVID-19 pandemic this fall, getting the flu vaccine is more important than ever. This will help prevent a “twindemic” — the collision of flu and COVID-19.

Cleveland Clinic study

In this recent study, a team of researchers led by Dr. Joe Zein used data from individuals enrolled in Cleveland Clinic’s COVID-19 Registry. This dataset includes all individuals who underwent testing for the disease at Cleveland Clinic, not just those who tested positive.

The team analyzed more than 13,000 people who received a test between March 8 and April 15, 2020.

The investigators compared those who had received adjuvant-free influenza vaccines in the fall or winter of 2019 (4,138 patients) with those who did not receive the vaccine (9,082 patients).

An adjuvant is an ingredient that manufacturers add to a vaccine to create a stronger immune response. However, adjuvanted vaccines can cause more side effects — including swelling, fever, and body aches — than adjuvant-free vaccines.

The findings revealed no difference in COVID-19 incidence or severity between people who received adjuvant-free influenza vaccines in the fall or winter of 2019 and those who did not receive the vaccine. Both groups had a comparable risk for hospitalization, admission to an intensive care unit, and death.

“[G]etting the annual flu vaccine remains the best safeguard against the influenza virus — both for yourself and the people around you.”

Thus, researchers and clinicians believe that the population’s adherence to widespread and early flu vaccination will help reduce the risk of simultaneous viral infections and epidemics or pandemics.

Further, the study team advises people to get the flu shot because this may result in fewer people with other COVID-19-like illnesses attending doctor’s offices and emergency departments.

“We have already seen the stress that COVID-19 can put on our hospitals and resources,” says Dr. Zein. “While we’re not yet sure how flu season will affect COVID-19 susceptibility and infections, we strongly advise people to get their influenza vaccines, both for their individual health and the collective health of our care systems,” he adds.

Although the findings affirm the safety and urgency of flu vaccination, the study authors acknowledge that much remains unclear about both the disease pathology and burden to the healthcare system of having concurrent SARS-CoV-2 and flu infections.

The authors hope that other scientists will collect surveillance data in the fall of 2020 to analyze the possible outcomes of coinfection and evaluate the interaction between influenza vaccinations and any newly developed vaccine against COVID-19 infection.