Since the early days of the pandemic, health officials have measured the threat of COVID-19 by comparing it to the flu.
At first, it wasn't even close. People hospitalized in 2020 with the then-new respiratory illness were five times more likely to die from their illness than patients who had been hospitalized with influenza during previous flu seasons.
Immunity from vaccines and past coronavirus infections has helped control COVID-19 to the point that when researchers compared the death rates of hospitalized COVID-19 and seasonal flu patients during the height of the season of influenza 2022-23, they found that the pandemic disease was only 61% more likely to cause death.
Now the same researchers have analyzed data for the fall and winter of 2023 and 2024. Dr. Ziyad Al-Aly, director of the Center for Clinical Epidemiology at the VA St. Louis Healthcare System, and his colleagues expected to find that the two respiratory illnesses had finally leveled out.
“There is a narrative that the pandemic is over, which is nothing,” Al-Aly said. “We came into this thinking we would do this rematch and find out that from now on it would be like the flu.”
The VA team examined the electronic medical records of patients treated at Veterans Affairs hospitals in all 50 states between October 1 and March 27. They focused on patients who were admitted because they had fever, difficulty breathing or other symptoms due to COVID-19. 19 or flu. (People who were admitted for another reason, such as a heart attack, and were later found to have a coronavirus infection, were not included in the analysis.)
COVID-19 patients were slightly older, on average, than flu patients (73.9 vs. 70.2 years) and were less likely to be current or former smokers. They were also more likely to have received at least three doses of the COVID-19 vaccine and less likely to have avoided the shots altogether.
However, after Al-Aly and his colleagues took into account these differences and a number of other factors, they found that 5.7% of COVID-19 patients died from their disease, compared to 4. .2% of influenza patients.
In other words, the risk of death from COVID-19 was still 35% higher than from the flu. The findings were published Wednesday in the Journal of the American Medical Association.
“It is undeniable that there is the impression that [COVID-19] it is no longer a major threat to human health,” Al-Aly said. “I think it is largely driven by opinion and the emotional desire to move beyond the pandemic, to leave everything behind. “We want to believe it’s like the flu, and we did, until we saw the data.”
Dr. Peter Chin-Hong, an infectious disease specialist at UC San Francisco, said the study results match what he sees at his hospital.
“COVID continues to make some people in our community seriously ill and die, even in 2024,” he said. “While most will not become seriously ill from COVID, for some people it will be like 2020 all over again.”
This is particularly true for older people, who have not received their most recent recommended COVID-19 booster, and who have not taken full advantage of antivirals like Paxlovid. Chin-Hong noted that only 5% of COVID-19 patients in the study had been treated with antivirals before being hospitalized.
Even if the death rates of COVID-19 and flu patients had been the same, COVID-19 would still be the biggest health threat because it is sending more people to the hospital, Al-Aly said.
Between October 1 and the end of March, 75.5 out of every 100,000 Americans had been hospitalized with the flu, according to the Centers for Disease Control and Prevention. During that same period, the COVID-19 hospitalization rate was 122.9 per 100,000 Americans, the CDC says.
“COVID continues to carry an increased risk of hospitalization,” Al-Aly said. “And among those hospitalized, more will die as a result.”
However, Al-Aly noted with frustration that while 48% of U.S. adults received the flu vaccine this year, only 21% of adults are up to date on their COVID vaccines. 19, according to the CDC.
Chin-Hong added that more than 95% of adults hospitalized with COVID-19 last fall and winter had not received their latest booster shot, according to the CDC.
Taking into account all the tools available to prevent hospitalizations and deaths, and especially the fact that they are readily available to patients in the VA system, the relative risk of death from COVID-19 of 35% compared to the flu was “surprisingly high,” China said. Hong said.
And it's not like the flu is a trivial health threat, especially for older people and the immunocompromised. It routinely kills tens of thousands of Americans each year, CDC data shows.
“The flu is a consequential infection,” Al-Aly said. “Even when COVID is equated to the flu, it is still sobering and significant.”
The researchers also compared the death rates of VA COVID-19 patients before and after December 24, when the Omicron subvariant known as JN.1 became the dominant strain in the United States. The difference was not statistically significant.
In just the last two weeks, JN.1 appears to have been surpassed by one of its descendants, a subvariant known as KP.2. It is part of a family of subvariants that has adopted the nickname “FLiRT”, a nickname that refers to some of the mutations that have arisen in the viruses' spike proteins.
So far, there is no indication that KP.2 is more dangerous than JN.1, Al-Aly said.
“Are the hospitals filling up? No,” she said. “Are emergency rooms across the country inundated with respiratory illnesses? No.” There are also no worrying changes in the amount of coronavirus detected in wastewater.
“When we look at all of these data streams, we see no ominous signs that KP.2 is something the general public needs to worry about,” Al-Aly said.
It's also too early to say whether KP.2 (or whatever comes next) will ultimately erase the mortality gap between COVID-19 and the flu, he added.
“Maybe when we do a rematch in 2025, that will be the case,” he said.
