Is COVID really the weirdest disease of all time?

I’ve asked this question a hundred times and I’ve heard my colleagues ask it about a thousand. The list of complications that we’re seeing in COVID-19 patients boggles the mind.

Loss of sense of smell, respiratory failure, blood clots, kidney disease, cardiac arrest, congestive heart failure, diarrhea, stroke, cytokine storm.

And this isn’t even a complete list.

So what explains why the pandemic that’s killing tens of thousands and crippling our economy happens to cause problems in essentially every organ system of the body?

Is this just the weirdest disease of all time?

Take a brief detour with me back to medical school diagnostic reasoning

We’re taught in medical school that a patient can have a diagnosis that falls into one of four mutually exclusive, collectively exhaustive categories, in descending order of frequency.

1. A common presentation of a common disease

2. An uncommon presentation of a common disease

3. A common presentation of an uncommon disease

4. An uncommon presentation of an uncommon disease

In other words, not everyone has the same symptoms when they have the same disease.

And it’s much more likely that you have weird symptoms of a common disease than typical symptoms of an uncommon disease.

The American Heart Association spends the month of February raising awareness about heart disease in women not just because women often have different symptoms of heart attacks than men do, but because heart disease is the biggest killer of women.

Not everyone’s body reads the textbook when it comes to the symptoms of disease they develop.

So what do you think is happening with COVID?

I’ve written before in this newsletter about how I think the manifestations of COVID-19 essentially boil down to two major areas - the direct effects of the virus causing damage to our bodies, and the unintended consequences of our immune response to the virus, the combination of which can lead to manifestations in essentially every organ system.

I spent some time reading through the medical literature on the flu to see how many of the complications we’re seeing from COVID have been described with the flu.

What I found surprised me.

For every manifestation of disease I could think of that I’ve either seen or read about with COVID, there’s a case report or case series that’s been published showing the same thing with the flu.

Blood clots? Check

Cardiovascular collapse (fulminant myocarditis)? Check

Loss of sense of smell (anosmia)? Check

Acute respiratory distress syndrome (ARDS)? Check

Diarrhea? Check

[The take home point here is NOT that COVID-19 is just like the flu - it isn’t. It’s indescribably worse. The point is that a disease can have all kinds of weird and unlikely manifestations.]

COVID isn’t a zebra, it’s just a huge herd of horses

There’s a saying in medicine, "when you hear hoofbeats, think horses, not zebras.” In other words, common things are common.

In the case of COVID, this means that when you have a million Americans infected with the same disease, you’re going to see some uncommon presentations of that disease.

In my opinion, what we’re seeing isn’t a reflection of a viral infection that’s weirder than all the other ones, it’s a reflection of a viral infection that’s spread more widely than all the other ones.

When the herd of horses is this big, there are bound to be a strange ones in there.