Covid-19 isn't "just a flu," with a study of hospital patients finding that the virus was still 60% deadlier than influenza last winter.
Greater immunity against the coronavirus, better treatments and different virus variants lowered covid's mortality risk to about 6% among adults hospitalized in the U.S. last winter from 17% to 21% in 2020, researchers at the Clinical Epidemiology Center of the Veterans Affairs St. Louis Health Care System in Missouri found. That was still much higher than the flu's death rate of 3.7%.
"This finding should be interpreted in the context of a two-to-three times greater number of people being hospitalized for covid-19 versus influenza in the US in this period," epidemiologist Ziyad Al-Aly and colleagues wrote in a letter Thursday in the journal JAMA.
The research is based on an analysis of electronic health records in databases kept by the Department of Veterans Affairs, which operates the largest nationally integrated health care system in the U.S.
Covid has drawn comparisons with influenza, another viral respiratory disease. The Centers for Disease Control and Prevention estimates that about 22,000 Americans died from the flu in the 2019-20 flu season, whereas covid killed about 350,000 in 2020.
Compared with flu patients, those hospitalized with covid had a greater risk of acute kidney injury, severe septic shock, life-threatening blood clots, and a range of dangerous cardiovascular complications, Al-Aly showed in a study in 2020.
Bleeding and clotting complications, which can lead to stroke and heart attack, are more common in covid patients, said Lekshmi Santhosh, an associate professor of clinical medicine at the University of California, San Francisco.
"People who are hospitalized with covid often tend to have more multi-organ system complications than with influenza," said Santhosh, physician and medical director of a post-covid clinic. "When folks are hospitalized with covid, they sometimes are 'tipping over' from a fragile baseline state of health."