DOD study raises tantalizing question: does flu shot increase vulnerability to coronaviruses?

Phenomenon known as virus interference flagged in DOD study just before COVID-19 burst.

Published: May 12, 2020 6:58pm

Updated: June 3, 2020 10:37am

Just a few short weeks before the COVID-19 pandemic burst into public view, a medical researcher published a study on military members who got the flu shot. At the time, it barely created a ripple but its findings are now likely to have a larger impact on the future policy debate over infectious respiratory viruses.

The study published by Dr. Gregory Wolff in Science magazine was entitled, “Influenza vaccination and respiratory virus interference among Department of Defense personnel during the 2017-2018 influenza season" and it addressed a suspected phenomenon known as "virus interference."

The question Wolff, who is with the Armed Forces Health Surveillance Branch Air Force Satellite at Wright-Patterson Air Force Base in Ohio, sought to answer was does the influenza vaccine, i.e. the flu shot, increase the potential for infections from other respiratory viruses. He had the perfect test population: military members who were mostly required to get the annual vaccine.

His findings were mixed: Overall the "receipt of influenza vaccination was not associated with virus interference” among the DOD personnel, he wrote. But he added: “Examining virus interference by specific respiratory viruses showed mixed results.” 

And here's the kicker. “Vaccine derived virus interference was significantly associated with coronavirus and human metapneumovirus. However, significant protection with vaccination was associated not only with most influenza viruses, but also parainfluenza, RSV, and non-influenza virus co-infections"

In other words, there was some evidence a flu shot recipient might be more vulnerable to a coronavirus although well protected against many other forms of infection.

First off, the study is not a repudiation of flu vaccines, as some vaccine opponents have tried to make it. In fact, it clearly showed flu shots make a huge difference not only against influenza but many other viruses.

Secondly, the study isn't specific to COVID-19, which emerged long after the study was completed. The findings were about other viruses in the coronavirus family that cause things like bad colds.

And third, the study is hardly definitive. Though peer reviewed, it is known as a retrospective study looking at a past study instead of a live trial.

But what the study contributes to the future policy debate is a marker that more research likely needs to be done to understand how people who get flu shots and contract a coronavirus might need to be treated.

Dr. William Schaffner, a preventative medicine professor in the Division of Infectious Diseases at Vanderbilt University School of Medicine, called the January study a  a “pinprick for future research.”

Schaffner told Just the News that Wolff's findings clearly merit more investigation, but then “came COVID-19 and everything COVID-19.”

“It is not a definite study rather a retrospective study which does not mean it is a poor study at all,” Schaffner said. “The investigators are very good, and Dr. Wolff recognizes the limitations of a retrospective study.”

The question not only has caught Schaffner's eye.

On Tuesday, Dr. Anthony Fauci, the government's chief of infectious disease research at NIAID, offered his own words of caution about virus interference from vaccines when he testified before the Senate.

“I must warn that there is a possibility of negative consequences where certain vaccines can actually enhance the negative effect of the infection,” he told lawmakers.

The Department of Defense provides a unique population for vaccination studies because mandatory vaccination against influenza is required of all DoD Active Duty and Reserve Component personnel.

Following the 1918 influenza pandemic that hit the U.S. military hard both in U.S. military camps and on the trains that transported soldiers across the country, as well as those serving overseas during World War I, the influenza vaccine was not discovered and administered to the U.S. military until 1938. 

This DoD 2017-2018 study was reviewed and approved by the Air Force Research Laboratory Institutional Review Board. 

The Department of Defense Global Respiratory Pathogen Surveillance Program (DoDGRS) was involved.

It was established by the Global Emerging Infections Surveillance and Response System (GEIS). 

Dr. Schaffner told Just the News that  the investigators are “excellent.”

“However because the focus now is on COVID-19,” says Schaffner, “it will probably be pursued as a line of investigation in the future.”

Just the News reached out to Dr. Wolff but he did not immediately respond for comment.

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