COVID-19: Case Fatality Rate Isn’t Enough
One of the ideas I hear being regurgitated by those who think that COVID-19 is a “scamdemic” or something similar is related to the Case Fatality Rate. These skeptics are saying something akin to:
Oh, only 1-2 out of a hundred people who get sick eventually die. This is negligible. Why be bothered?
At first glance, there may be a valid basis for this. Let’s look at some numbers.
Specific Case Fatality Rates of particular diseases if left untreated or unvaccinated for include:
Bubonic Plague – 60%
Spanish Flu (1918) – 2.5%
Ebola – 90%
Naegleriasis – >99%
Smallpox – 95%
Seasonal Influenza – 0.1%
HIV/AIDS – 80%
Dengue Fever – 26%
Malaria – 0.3%
Typhoid – 10-20%
SARS – 9-11%
MERS – 34.4%
COVID-19 – ~0.8-9.6* (variable estimates due to ongoing pandemic)
It seems then that at best, less than one out of a hundred will die. At worst, one out of ten. Most estimates peg it at around 4%. In the Philippines as of this writing, it is somewhere between 2-%.
So COVID-19 only apparently kills less than MERS and the like. Also, I heard that few actually get sick?
In China, physicians have been coping with COVID-19 for over 3 months. Most of the people who contracted COVID-19 presented with mild symptoms (80.9%), then severe (13.8%), and finally critical (4.7%) Shang, Y., Pan, C., Yang, X. et al. Management of critically ill patients with COVID-19 in ICU: statement from front-line intensive care experts in Wuhan, China. Ann. Intensive Care 10, 73 (2020). https://doi.org/10.1186/s13613-020-00689-1
Mild symptoms can be so mild that they can be ignored. I have a pulmonologist friend in New York who told me that, while he tested positive, his only symptom was a lingering cough.
So what’s the big deal if only a few get really sick of COVID-19, and only a few die?
Ah but is it true that only a few get sick? The thing about a disease such as COVID-19 as opposed to, let’s say, MERS or EBOLA, is that COVID-19 spreads easily.
MERS or EBOLA kills quickly and rapidly, and so it doesn’t spread as fast. In fact, EBOLA kills too quickly and people die before they infect too many others.
Wait, this sounds familiar…
Plague Inc. is a game published by Ndemic Creations.
The game Plague Inc lets you simulate a disease causing germ. In it, if the germ kills victims too fast, then the germ dies out before it spreads too far.
Part of my personal strategy in playing this game is maximizing infectivity while sacrificing it’s killing ability. This seems to be what COVID is doing.
COVID-19: The Perfect Combination?
COVID-19 doesn’t make everyone it infects sick. If it does, it makes them only mildly ill, enough to make the patient think it’s hardly worth a bother. As such, these patients can thus unknowingly infect others. Then, once it hits a vulnerable victim – kaboom.
Now let’s look at the numbers. For the sake of simplicity, let’s take a Case Fatality Rate of 4%, a symptomatic rate of 80% and a critical case rate of 20%.
In a population of 10,000 people, that translates to 8000 with symptoms, 2000 needing critical care, and 400 dead.
In a population of 100,000 people, that means 80,000 with symptoms, 20,000 needing critical care, and 4000 dead.
Imagine if we go to the millions.
And that doesn’t even take into account the economic burden for those who do get sick.
Recovering from illness doesn’t mean doing nothing and waiting for patients to get well. We physicians have to do something, too! In this case, patients need to have machines help them breathe.
Roughly 20 percent of symptomatic covid-19 patients require hospitalization and about 5 percent end up in the ICU. Most of those in intensive care require ventilators. The devices essentially breathe for the patient, who is sedated with a long plastic tube placed down the throat and into the windpipe. Severely ill covid-19 patients tend to linger on ventilators longer than other intubated patients, some for weeks. The tube inflames tissue, which can interfere with breathing, so later in the course of convalescence it may be removed and replaced by a smaller tube inserted through an incision in the windpipe. https://www.inquirer.com/health/coronavirus/coronavirus-covid-19-ventilator-patients-survival-rates-increase-20200703.html
Mechanical Ventilation isn’t like just putting on an oxygen mask. It means putting a tube directly into one’s windpipe.
A laryngoscope is used to keep the airway open while putting a breathing tube in.
Imagine being like this for weeks at a time:
And even if one doesn’t die, one can still have complications.
According to this article from vox.com, COVID-19 Survivors face long term effects:
Strokes, Embolisms, Blood Clotting
Neurocognitive and Mental Health Impact
A Final Word:
As one can see, it’s obviously not enough just to look at the Case Fatality Rate. We must look at the notion of how many can get infected and spread the virus, the cost of treatment and medical care, and post recovery complications.
At this point, we may be too early in the epidemic to know the impact of these factors. It took us years to fully understand diseases like HIV-AIDS. Nonetheless, it is crystal clear that we cannot risk underestimating COVID-19 just because it “only kills a few people”.