COVID comorbidities are not analogous to car crashes: Debunking the 6% mortality claim

CDC COVID twitter tweet #only 6%Recently, the CDC released data on COVID comorbidities, including data showing that 6% of COVID-19 deaths only listed COVID on the death certificate, while the remaining 94% of COVID deaths also listed other conditions. Many have jumped on this as proof that COVID is far less deadly than previously claimed, and they are arguing that most reported COVID deaths are actually just people who died of some other condition while happening to have COVID. In particular, I keep seeing an analogy of someone who has COVID getting hit by a car, then the death being attributed to COVID. This is a very bad analogy (and faulty argument in general) that horribly mischaracterizes these data. So, I want to briefly explain what is actually going on.

First, you need to realize that when a patient dies, doctors list all of the factors that contributed to the death. This often includes multiple conditions, at which point we call them “comorbidities.” In the case of COVID, two main things are happening. First, in some cases, people have a pre-existing condition that interacts with COVID and makes them more likely to die from COVID. Second, COVID leads to conditions that then contribute to the death.

Let’s start with the pre-existing condition situation. We know that people with some health conditions are more prone to die from COVID than people without those conditions, because those conditions make them more vulnerable to COVID. Thus, there is an interaction between COVID and the pre-existing condition, with both contributing to the death. Importantly, however, in most cases, the person would not have died at this particular point in time had it not been for COVID. In other words, something like an existing respiratory problem makes people more sensitive to COVID, resulting in a higher death rate when infected with COVID. That does not mean that COVID wasn’t a key factor in their deaths. It is simply that it was not the only factor.

By way of analogy, imagine that someone with asthma gets trapped in an environment with lots of smog, ultimately resulting in an inability to breathe and subsequent death. What killed them? Well, both the asthma and the smog played a role. The smog was a serious problem because of the asthma, but conversely, they could have kept on living with the asthma had it not been for the smog. If we could have prevented them form being exposed to the smog, they would have lived.

Even so, for many people, COVID is fatal because of interactions with other conditions, but that still means that COVID was fatal. It still means that they would have lived had it not been for COVID.

To give one final analogy, imagine a disease that is far deadlier in men than in women. Imagine that we look at the mortality statistics form that disease and see that 94% of deaths were from men. It would clearly be absurd to say, “they didn’t die form the disease, it was being a male that killed them.” That would obviously be nuts. It would be apparent to everyone that there was an interaction between the disease and sex that causes men to be more sensitive to it. Even so, there are interactions between many pre-existing conditions and COVID that make people with those conditions more sensitive to COVID and more likely to die from it.

On the flip side, many of the reported comorbidities are actually caused by COVID. Look at the data from the CDC. The single most common comorbidity category* (68,004) was influenza/pneumonia. These diseases are often secondary infections that happen as a result of viral infections. Similarly, respiratory failure was present in 54,803 cases. Again, this is something that we know COVID causes. So many of these comorbidities are actually caused by COVID!

*Technically, the most common category was “other” which includes a very wide range of conditions that were grouped together because each was too uncommon to merit its own category. Thus the influenza/pneumonia category was the most common category for discrete diseases, rather than the large hodgepodge of conditions.

By way of analogy, the argument being made by science deniers is no different from someone bleeding out from a gunshot wound, then someone else saying, “bullets aren’t dangerous, because she died from blood loss, not the bullet.” That’s obviously a dumb argument. She only lost the blood because of the bullet. Even so, many people are only dying from conditions like respiratory failure or heart failure because of COVID19.

It is also worth noting that, as is often the case, this argument is straight out of the anti-vaccine playbook. For diseases like measles, secondary infections with diseases like pneumonia often contribute to children’s deaths. Thus, anti-vaccers incorrectly argue that measles isn’t deadly because the pneumonia is what killed them. Just like COVID and my gunshot example, however, they only developed pneumonia because of measles.

So now, with all of that in place, let’s circle back the analogy of someone getting hit by a car. I like analogies a lot. I have frequently argued that they are valuable for testing whether consistent reasoning is being applied. However, as I have explained before, for the analogies to be useful, they must follow the same logical structure as the original argument. That is very clearly not the case here. Someone who happens to have COVID getting hit by a car is a very, very different thing from either someone with a pre-existing condition that predisposes them to complications from COVID dying from an interaction between the condition and COVID or COVID itself causing a secondary condition.

Do you see the difference? The vast majority of comorbidities listed are directly related to COVID either as a factor that exacerbates the situation or as a result of COVID. In contrast, the car accident has nothing to do with COVID. They are not analogous, and anyone who would use such a clearly terrible argument obviously does not know what they are talking about.

Having said all of that, there are almost certainly some cases in this database where COVID truly wasn’t the cause. There are probably some cases where someone who had COVID just happened to have a heat attack that would have happened without the COVID, or where someone who had COVID was in an accident, but when you start looking closely at the data, those are clearly a very tiny minority, and the vast majority of comorbidities relate to COVID. Indeed, beyond these data and all the data looking at how COVID attacks the body, we also know that there have been far more deaths this year in the US than there were during the same time period last year (Weinberger et al. 2020). Indeed, there are more excess deaths than the total number of reported COVID deaths. Understanding exactly what that means is very complicated because there are many contributing factors. We may be underestimating COVID deaths, but also, there may be increased deaths due to factors like people not seeking medical help for conditions for which they normally would seek help. Conversely, things like a decrease in car accidents could pull the number the other direction. However, several pieces of evidence (such as a spike in excess deaths in places that had large outbreaks with many reported COVID deaths; e.g., New York city) indicate the COVID is a key factor in the number of excess deaths seen this year, and it is very unlikely that we are grossly overestimating the COVID mortalities.

As others have pointed out, the correct way to look at this 6% figure is not that only 6% of reported COVID deaths were actually from COVID. Rather, it means that of all the people who died from COVID, 6% did not have any other reported conditions. In other words, these data show that some people are more vulnerable to COVID than others due to existing health conditions (which we already knew) and COVID often results in secondary problems which contribute to patients’ demise (again, which we already knew). Stop trying to twist science to fit your personal agenda and look rationally at the facts. Think critically and don’t blindly believe something just because you saw it on Facebook or Twitter.

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