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April 08, 2023
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COVID-19 remained deadlier than flu this past season

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Key takeaways:

  • Being hospitalized for COVID-19 vs. seasonal influenza was associated with an increased risk for death.
  • Risk for death was greater among unvaccinated people compared with patients who were vaccinated or boosted.

COVID-19 remained deadlier than influenza this past season, although the difference in mortality shrunk compared with past years, according to a study comparing outcomes of patients hospitalized with the illnesses.

“In the first year of the COVID-19 pandemic, two U.S. studies suggested that people hospitalized for COVID-19 had nearly five times the risk of 30-day mortality compared with those hospitalized for seasonal influenza,” Yan Xie, PhD, senior clinical epidemiologist at the Saint Louis VA Health Care System’s Clinical Epidemiology Center, and colleagues wrote.

IDN0423Xie_Graphic_01_WEB
Xie Y, et al. JAMA. 2023;doi:10.1001/jama.2023.5348.

“Since then, much has changed, including SARS-CoV-2 itself, clinical care, and population-level immunity; mortality from influenza may have also changed,” Xie said and colleagues wrote.

Because of this, the researchers sought to determine if COVID-19 was still associated with a higher risk for death compared with seasonal influenza during the fall and winter of 2022-2023.

According to the study, the researchers used patient data from the U.S. Department of Veterans Affairs electronic health databases to assess patients with at least one hospital admission between 2 and 10 days after a positive SARS-CoV-2 or influenza test and admission diagnosis for COVID-19 or influenza between Oct. 1, 2022, and Jan. 31, 2023. All patients were followed until death or through March 2, 2023.

In total, there were 8,996 hospitalizations for COVID-19 and 2,403 hospitalizations for seasonal influenza. They researchers determined that hospitalization for COVID-19 was associated with a higher risk for death (HR = 1.61; 95% CI, 1.29-2.02) compared with hospitalizations for influenza. They added that the mortality rate at 30 days was 5.97% for COVID-19 and 3.75% for influenza, with an excess death rate of 2.23% (95% CI, 1.32%-3.13%).

The authors wrote that this finding “should be interpreted in the context of a two to three times greater number of people being hospitalized for COVID-19 vs. influenza in the U.S. during the assessed timeframe.”

Additionally, the study showed that the overall risk for death decreases as vaccinations increased (P = .009 for interaction between unvaccinated and vaccinated; P < .001 for interaction between unvaccinated and boosted), which the authors said further highlights the importance of vaccination.

“The difference in mortality rates between COVID-19 and influenza appears to have decreased since early in the pandemic; death rates among people hospitalized for COVID-19 were 17% to 21% in 2020 vs. 6% in this study, while death rates for those hospitalized for influenza were 3.8% in 2020 vs. 3.7% in this study,” the authors wrote. “The decline in death rates among people hospitalized for COVID-19 may be due to changes in SARS-CoV-2 variants, increased immunity levels (from vaccination and prior infection) and improved clinical care.”