Influenza vaccine in COVID-19 patients: Who?, why?, when?

Abstract

Considering the increased prevalence of influenza infections in the cold season and the pandemic evolution of severe acute respiratory syndrome-CoV-2 (SARS-CoV-2), the medical staffs are facing potential viral co-infection with SARS-CoV-2 and influenza virus. Both viruses belong to the category of ribonucleic acid (RNA) viruses, having common structural features, causing a similar immune response, with a related mode of transmission and with both respiratory and general symptoms. SARS-CoV-2 and influenza viruses cause contagious infections and the protective measures against them are the same: wearing masks in crowded spaces, proper hand hygiene and avoiding crowded places. Co-infections with influenza A and B viruses and SARS-CoV-2 virus involve additional precautions regarding the therapeutic and evolution approach. Studies show that patients who have been vaccinated against influenza have developed milder forms of confirmed SARS-CoV-2 infection. In elderly patients, increased influenza vaccination coverage has shown to be associated with a decrease in mortality rate and also reduced the heavy impact of double infection. The Influenza vaccine can trigger early immune mechanisms in order to facilitate early detection of SARS-CoV-2 as well as its clearance. Influenza vaccination should now be seen, more than ever, as a strategy to combat the growing SARS-CoV-2 pandemic, especially in vulnerable populations (elderly and people with associated comorbidities).