Flu Vaccine Protects Against Severe COVID-19, Study Suggests

In yet another recent finding, researchers have reported that vaccines apart from those specifically targeting COVID-19 can also confer a protective response, especially against getting disease severity.

Researchers at Weill Cornell Medicine-Qatar, a branch of Weill Cornell Medicine of Cornell University, New York, found that influenza vaccines have a surprising benefit in terms of protecting COVID-19 patients from severe diseases. The findings have been published in the preprint server medRXiv, which is yet to be reviewed by peers.

The research was started between September and December 2020, when vaccines against COVID-19 had not even been rolled out.

The study considered a relatively large cohort comprising more than 30,000 healthcare workers. Participants who got an influenza vaccine were found to be almost 90% less likely to develop severity of COVID-19 and the effects were there for a few months. They fared better than the unvaccinated workers.

The vaccinated group had a median age of 36 years and the unvaccinated 35 years. Participants who received the Quadrivalent Influvac Tetra vaccine, manufactured by Abbott, were tested for the presence of SARS-CoV-2, which drove the pandemic at a median 1.5 months from the time of vaccination. The authors wrote, “The estimated effectiveness of influenza vaccination against SARS-CoV-2 infection >14 days after receiving the vaccine was 29.7%. The estimated effectiveness of influenza vaccination against any severe, critical, or fatal COVID-19 was 88.9%.”

The research was parallel to some previous ones which suggest that strengthening the immune system with an influenza jab may enable the body to fight off the coronavirus. In the early days of the pandemic, researchers were intense in their hunt for the possibilities of existing vaccines being effective in providing protection against COVID-19. However, gathering strong evidence was not that easy because those who received vaccines other than against COVID-19 also made other choices that reduce the risk of infection amongst them.

To better test this, the team of researchers, led by Laith Jamal Abu-Raddad, who is an infectious disease epidemiologist at Well Cornell Medicine-Qatar, analysed the health records of more than 30,000 health workers in the country.

“This is an important piece of evidence. The observation that influenza vaccines are linked to a reduction in not just SARS-CoV-2 infections but also disease severity strongly suggests that the protection is genuine,” said Mihai Netea, an infectious-disease specialist at Radboud University Medical Center, Netherlands.

However, the longevity of the protection provided by the flu vaccine remains inconclusive. In the Qatar study, the team found that the SARS-CoV-2 infection occurred about six weeks after receiving the flu vaccine. Abu-Raddad thinks that the protection should not last too long whereas Netea guesses that the protective benefits can last beyond six months.