#16,104
Three weeks ago, in ECCMID: Flu Jab May Provide Some Protection Against Severe Effects Of COVID, we looked at a press release on a presentation of an unpublished study at the 31st ECCMID Conference that found that those who received a flu vaccine within 6 months of contracting COVID appeared significantly less likely to experience severe disease.A few similar studies include:While the mechanisms behind any potential benefit are unknown, we've seen a few studies suggesting that - at least statistically - receipt of the flu vaccine has been linked to lower SARS-CoV-2 infection rates, and/or reduced severity.
- Last year, in the preprint The effect of influenza vaccination on trained immunity: impact on COVID-19, researchers from the Netherlands hypothesized that receipt of the quadrivalent flu vaccine could boost innate immunity after finding SARS-CoV-2 infection `. . . was less common among Dutch hospital employees who had received influenza vaccination during the 2019/2020 winter season (RR = 0,61 (95% CI, 0.4585 - 0.8195, P = 0.001).'
- Similarly, last January researchers from the University of Missouri School of Medicine published The Flu Vaccination May Have a Protective Effect on the Course of COVID-19 in the Pediatric Population, finding that children vaccinated against flu were less likely to be symptomatically infected with SARS-CoV-2 (p=0.028, adj. OR=0.714, 95% CI [0.529, 0.964]) than those not vaccinated
- And yet another study, Inactivated trivalent influenza vaccination is associated with lower mortality among patients with COVID-19 in Brazil, looking at over 53,000 hospitalized COVID patients during the first half of 2020, found mortality was consistently lower among patients who received a flu vaccine after March 1st, 2020.
- And last March, in AJIC: Impact of the Influenza Vaccine on COVID-19 Infection Rates and Severity, we saw another study that found that receipt of the flu vaccine appears to be linked to reduced infection, and severe illness, with COVID-19.
This latest study has now been published in PloS One (see link and Abstract below), and is available to read in its entirety.
Examining the potential benefits of the influenza vaccine against SARS-CoV-2: A retrospective cohort analysis of 74,754 patients
Susan M. Taghioff , Benjamin R. Slavin , Tripp Holton, Devinder Singh
Published: August 3, 2021
https://doi.org/10.1371/journal.pone.0255541Abstract
Introduction
Recently, several single center studies have suggested a protective effect of the influenza vaccine against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This study utilizes a continuously updated Electronic Medical Record (EMR) network to assess the possible benefits of influenza vaccination mitigating critical adverse outcomes in SARS-CoV-2 positive patients from 56 healthcare organizations (HCOs).
Methods
The de-identified records of 73,346,583 patients were retrospectively screened. Two cohorts of 37,377 patients, having either received or not received influenza vaccination six months–two weeks prior to SARS-CoV-2 positive diagnosis, were created using Common Procedural Terminology (CPT) and logical observation identifiers names and codes (LOINC) codes. Adverse outcomes within 30, 60, 90, and 120 days of positive SARS-CoV-2 diagnosis were compared between cohorts. Outcomes were assessed with stringent propensity score matching including age, race, ethnicity, gender, hypertension, diabetes, hyperlipidemia, chronic obstructive pulmonary disease (COPD), obesity, heart disease, and lifestyle habits such as smoking.
Results
SARS-CoV-2-positive patients who received the influenza vaccine experienced decreased sepsis (p<0.01, Risk Ratio: 1.361–1.450, 95% CI:1.123–1.699, NNT:286) and stroke (p<0.02, RR: 1.451–1.580, 95% CI:1.075–2.034, NNT:625) across all time points. ICU admissions were lower in SARS-CoV-2-positive patients receiving the influenza vaccine at 30, 90, and 120 days (p<0.03, RR: 1.174–1.200, 95% CI:1.003–1.385, NNT:435), while approaching significance at 60 days (p = 0.0509, RR: 1.156, 95% CI:0.999–1.338). Patients who received the influenza vaccine experienced fewer DVTs 60–120 days after positive SARS-CoV-2 diagnosis (p<0.02, RR:1.41–1.530, 95% CI:1.082–2.076, NNT:1000) and experienced fewer emergency department (ED) visits 90–120 days post SARS-CoV-2-positive diagnosis (p<0.01, RR:1.204–1.580, 95% CI: 1.050–1.476, NNT:176).
Conclusion
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. 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.
While no substitute for getting the COVID vaccine, these studies appear to show some additional, and unexpected, benefits against severe illness from SARS-CoV-2 infection.
Given the uncertainties raised by new, emerging variants, and the possible decline in protection from the COVID vaccine over time, this ought to provide a little extra incentive to get the flu vaccine this fall.
For a less technical read, you may wish to peruse the media release from the University of Miami's Miller School of Medicine.
Miller School Research Reveals that Flu Shot Protects Against Severe Effects of COVID-19
Written by Kai Hill
Published August 3, 2021
Reading Time: 4 minutes
In a newly published study, physician-scientists at the University of Miami Miller School of Medicine have shown that the flu vaccine may provide vital protection against COVID-19.
