A new study suggests that the flu vaccine may provide vital protection against COVID-19.
The University of Miami Miller School of Medicine led the study, entitled, “Examining the Potential Benefits of the Influenza Vaccine Against SARS-Cov-2.” Their retrospective cohort analysis of 74,754 patients was published recently in the peer-reviewed scientific journal PLoS One.
Results indicate that an annual flu shot reduces the risks of stroke, sepsis, and deep vein thrombosis (DVT) in patients with COVID-19, while also making it less likely that they would have to visit the emergency department (ED) or end up in the intensive care unit.
“Only a small fraction of the world has been fully vaccinated against COVID-19 to date, and with all the devastation that has occurred due to the pandemic, the global community still needs to find solutions to reduce morbidity and mortality,” explained senior study author Devinder Singh, MD, of the Miller School.
Preliminary data of the study was presented at the European Congress of Clinical Microbiology & Infectious Diseases.
The authors point out that single-center studies have signaled a protective effect of the influenza vaccine against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Their study used a continuously updated electronic medical record network to assess the possible benefits of influenza vaccination in curbing critical adverse outcomes in SARS-CoV-2-positive patients from 56 healthcare organizations.
Researchers screened de-identified records of 73,346,583 patients and created two cohorts of 37,377 patients. All those participants had either received or not received influenza vaccination 6 months to 2 weeks prior to a SARS-CoV-2-positive diagnosis. The study team compared adverse outcomes between cohorts within 30, 60, 90, and 120 days of positive SARS-CoV-2 diagnosis. Those included sepsis; strokes; DVT; pulmonary embolism; acute respiratory failure; acute respiratory distress syndrome; arthralgia or joint pain; renal failure; anorexia; heart attack; pneumonia; emergency-department visits; hospital admission; ICU admission; and death.
Propensity score matching took into consideration age, race, ethnicity, gender, hypertension, diabetes, hyperlipidemia, chronic obstructive pulmonary disease, obesity, heart disease, and lifestyle habits such as smoking, the study notes.
Results indicate that SARS-CoV-2-positive patients who received the influenza vaccine experienced decreased sepsis (P <.01; risk ratio [RR]: 1.361-1.450; 95% CI, 1.123-1.699; number needed to treat [NNT]: 286) and stroke (P <.02; RR: 1.451-1.580; 95% CI;1.075-2.034; NNT: 625) across all time points. In addition, researchers report that ICU admissions were lower in SARS-CoV-2-positive patients receiving the influenza vaccine at 30, 90, and 120 days (P <.03; RR: 1.174-1.200; 95% CI, 1.003-1.385; NNT: 435), while approaching significance at 60 days (P = .0509; RR: 1.156; 95% CI, 0.999-1.338).
Furthermore, they point out that patients who received the influenza vaccine experienced fewer DVTs 60-120 days after positive SARS-CoV-2 diagnosis (P <.02, RR:1.41-1.530; 95% CI,1.082-2.076; NNT: 1,000) and needed fewer ED visits 90-120 days post SARS-CoV-2-positive diagnosis (P <.01, RR:1.204-1.580; 95% CI, 1.050-1.476; NNT: 176).
The differences were significant, with those who had not received flu shots:
• Up to 20% more likely to have been admitted to the ICU
• Up to 56% more likely to visit the ED
• Up to 45% more likely to develop sepsis
• Up to 58% more likely to have a stroke
• Up to 40% more likely to be diagnosed with DVT
Risk of death was not reduced, however.
“Our analysis outlines the potential protective effect of influenza vaccination in SARS-CoV-2-positive patients against adverse outcomes within 30, 60, 90, and 120 days of a positive diagnosis,” the authors conclude. “Significant findings favoring influenza vaccination mitigating the risks of sepsis, stroke, deep vein thrombosis (DVT), emergency department (ED) & Intensive Care Unit (ICU) admissions suggest a potential protective effect that could benefit populations without readily available access to SARS-CoV-2 vaccination. Thus, further investigation with future prospective studies is warranted.”
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