Covid vs. Influenza Wars: 2024 update.
“Is Covid-19 just like the flu now?” We hear this question often, don’t we?
While (spoiler alert!) Covid is still the deadlier pathogen, the answer is increasingly complicated. In 2020, the analysis was far less complicated. Covid-19 was hospitalizing and killing far, far more people than seasonal flu ever does. That was true both in raw numbers and on a per-case basis. Back in 2020, research found that around 18%-21% of patients hospitalized for Covid-19 were dying, compared to 3.8% of patients hospitalized for influenza. Other datasets had similar findings.
But by now, the population has more immunity to Covid-19 from vaccines and prior infections than we had at first (read: none). Plus we have some therapeutics that can still help some high-risk people. (Our flu therapeutics are not great, it bears mentioning, and the vaccines we have are effective, but vary year by year.)
So, the most honest and coherent answer I have to the Covid vs flu question is this: the effects these pathogens have at the population level have become much more similar over time.
New research in the Journal of the American Medical Association provides an update. Using Veterans Administration (VA) data, researchers found that in 2023-2024, patients hospitalized for Covid-19 were still around 35% more likely to die in the following 30 days (out of every 100 patients hospitalized for Covid, 5.7 of them died, compared to 4.2 out of 100 patients hospitalized for influenza.)
Key insights and context:
The Covid-related fatality rate among hospitalized patients has dropped substantially. In 2020, the rate was around 19%—a staggering figure. So, a 5.7% “hospital fatality rate” (deaths per 100 hospitalizations) for Covid is a major improvement, if still scary high. But keep in mind, this is not the infection fatality rate (IHR) (which would be deaths per 100 infections). The IHR for Covid is far lower.
Compared to VA 2022-2023 season data from the same researchers, the comparison between Covid and flu narrowed just a bit this year. This is both because the Covid-19 hospital fatality rate fell a bit this season and because the influenza hospital fatality rate rose compared to last season. In 2022-2023, those hospitalized with Covid were around 61% more likely to die in the next 30 days (5.97% among Covid-19 hospital admissions vs 3.75% among influenza hospital admissions). So, the 2023-2024 findings—with Covid hospital patients “only” 35% more likely to die—seem to suggest some improvement.
This study assessed a very high risk group. That is, VA patients (who tend to have a lot of medical problems) with an average age of around 74. The fatality rate among people hospitalized with Covid is lower in healthier people (and far lower in people who are both younger and healthier).
Something the VA researchers mentioned in their latest study is that while the fatality rate among hospitalized Covid and influenza patients are closer than ever, Covid still was responsible for nearly double the hospitalizations this season (though the peak of flu did top the Covid peak, Covid led the overall tally by far; Covid apparently remains more transmissible in humans at present). So, to use a baseball analogy, we have to keep in mind the difference between hits (which increases with more number “at bats”—that is, infections) and batting average (which does not).
Bottom line:
Covid remains responsible for more hospitalizations than flu, in large part because, despite the populations’ increasing immunity to Covid over time, it is still causing more infections.
That said, on a head-to-head basis, Covid and influenza outcomes are becoming more similar each year, though Covid still has the edge. While Covid remains the deadlier pathogen among high-risk hospitalized patients, the difference has narrowed vastly. A 35% increased mortality rate among hospitalized patients is a lot better than what we were seeing early in the pandemic—which was more like a 500%-650% increased mortality risk when comparing Covid and flu hospitalizations.
Both Covid and influenza cause a variety of secondary problems (including those leading to hospitalization) and longer-term illnesses. These data don’t measure that directly.
Lastly, when people ask “Is Covid-19 just like the flu now?” I often worry that what they’re really asking is, “Can we ignore Covid now?” The answer to that is no. We should have been doing a better job with flu in 2019! The goal is to do better than that with all deadly pathogens, not to lapse to our previous lackluster responses.
Questions? Insights? Please add them in the Comments section!
Thanks again for speaking truth outwardly. Pulitzer-winning science journalist, Laurie Garrett, wrote books and articles warning of a coming pandemic and not just one, before COVID. She also wrote a book of the falling apart of Public Health. Epidemiologists around the world did the same. We were forewarned even locally. I had a friend that worked as an administrator in a major hospital system here, in Western MA who called me at the very beginning of COVID (pre-vaccine) knowing I was highly immune-compromised many times over between the immune-suppressing Rx I was on for Progressive MS, and the Primary Immune disease I had called CVID, ,etc. He warned me that the "industry" knew that something like this was coming and they were finally and already (pre-COVID) assessing preparedness things like ventilator inventory. My hospital and others were quite short on ventilators. He told me not to come into the hospital as I would not be prioritized for one because of my health issues and because I was over 60 and I would be isolated from my husband and family. Flash forward 4 years and we are living in Disneyland of Denial again, already, as you (and Katelyn Jetalina) have stated. Mostly because pandemics are a political "hot potato" during a scary Presidential Election year and much of society is still in PTSD and dreads the thought of another shutdown, especially the able-bodied, and CEO's. But we can't afford to be such ostriches right now and squander an opportunity to learn.
The final paragraph says it all, for me: "Can we ignore Covid now?” The answer to that is no. We should have been doing a better job with flu in 2019! The goal is to do better than that with all deadly pathogens, not to lapse to our previous lackluster responses."