A new medical study that has not yet been peer-reviewed suggests that getting your flu shot could help protect against getting COVID-19 as well.
According to the study, the phenomenon of cross-protection – when the body’s immune response to one disease helps it fight off another as well – might extend to influenza and SARS-CoV-2, the virus that causes COVID-19.
The research was conducted by a team of scientists at Radboud University Medical Center in the Netherlands, who published their work on MedRxiv, a pre-print server for papers. A disclaimer atop the report notes: “This article is a preprint and has not been peer-reviewed. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.”
“Using an established in-vitro model of trained immunity, we demonstrate that the quadrivalent inactivated influenza vaccine used in the Netherlands in the 2019-2020 influenza season can induce a trained immunity response, including an improvement of cytokine responses after stimulation of human immune cells with SARS-CoV-2,” the researchers write.
The study reports that among some 10,600 Radboud hospital employees, 2.23% of those who did not get the flu shot during the previous winter contracted COVID-19, while only 1.33% of those who received a flu shot got the novel coronavirus.
Mihai Netea, an infectious disease immunologist at Radboud who co-authored the study, told Scientific American that while the results might be conflating correlation with causation, a true clinical trial would require randomly denying a control group their flu shots. “That’s not ethical,” he said.
According to an editorial accompanying the study, while giving patients the blood of people who survived COVID-19, which is laced with the antibodies their bodies used to fight off the virus, seemed to have some effect on alleviating some symptoms of the virus, the method of plasma therapy itself likely amplifies the thrombotic effects of COVID-19, making the patient’s blood even thicker and more prone to clotting.