The SARS-CoV-2 Coronavirus Discriminates

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Note: This is a previously unpublished post I wrote in early 2020. I'm posting it now (late 2022) as a reminder that critical thinking based on existing scientific knowledge turned out to be right, while the "experts" were wrong. Your worldview matters. The "experts'" by and large operate on an evolutionary, progressive worldview that borders on magical thinking. This led them to believe that SARS-2 was capable of doing things no virus in history has been able to do. At the same time, they blindly denied the scientific and common-sense knowledge that masks could not stop an airborne virus. Science-denial, magical thinking, and superstition were hallmarks of "the experts". In the end, they were wrong, and traditional (evidence-based) thinking about disease and epidemics was right. Many of the "experts" were imposters, and not true experts at all.

Like HIV, the novel coronavirus (SARS-CoV-2) discriminates harshly against certain people and spares others. In healthy individuals, this coronavirus tends to spread more easily than the flu, but is less severe. In unhealthy individuals, who tend to be older, smoke, or have preexisting health conditions, the virus tends to spread less easily than the flu, but is more severe.

Spread and Severity are Inversely Proportional

Virologists have known for a long time that as a general rule, the more lethal a virus is, the less easily is spreads. A good example of this is rabies which is highly lethal, but which does not spread easily (you have to be bitten to get it).

On the flip side, the less virulent a virus is, the easier it spreads. Common cold viruses are a... common example. Everyone has gotten a cold, and almost nobody has serious complications from it.

But this is a generalization, and we need to be more specific. Viruses don't spread by themselves. They need a host, so how easily a virus spreads and how severe it is depend on the host. After being in the US for at least two months, it's clear that the novel coronavirus (SARS-CoV-2) causes mild or no symptoms in healthy, young people, and very severe symptoms in unhealthy people, particularly the elderly. We can break down this distinction between healthy and unhealthy recipients of the virus as follows:

Healthy Unhealthy
Mild symptoms Severe symptoms
Good outcomes Poor outcomes
Young (< 50 years) > 50 years
Never-smoker Smoker
No pre-existing health conditions Hypertension, heart or lung disease, diabetes

To sum it up, if you're young and healthy, then your risk of suffering serious complications from the virus is lower than that of the flu. On the other hand, if you're unhealthy, you're at a much greater risk of needing more intense medical treatment should you become infected. If you do have severe symptoms, however, you're less likely to spread it because you're going to avoid others, and they're going to avoid you.

Now here's the good news. About 2/3 of the US population is under 50, and tend to have better outcomes with this novel coronavirus. Younger people move around more, and are thus more likely to contract it and develop immunity to it. Therefore, even though a lot of people under 50 will likely get infected, most of those infections will result in mild symptoms and herd immunity that will protect the unhealthy population. This is the principle behind vaccinations, and we know it works.

Here is the bad news: as the virus spreads, unhealthy, high-risk people will inevitably get it. Isolation is especially important for unhealthy people until herd immunity develops in the less vulnerable population. Sadly, we seems to be taking the opposite approach. Stores are encouraging senior citizens to shop together by setting special store hours just for them! This is a terrible idea. Strangely, in some states, if those same senior citizens wanted to meet at a restuarant for coffee and conversation, they wouldn't be allowed to.

The Diamond Princess: A Petri Dish

The novel coronavirus causes severe symptoms in a fair number of vulnerable people, so we can be quite certain that it doesn't spread nearly as easily as many people fear. But just how easily does it spread? The Diamond Princess cruise ship is an instructive example.

Coronavirus infections broke out on this ship of over 3,700 passengers, about 712 of whom tested positive. That's about a 19% infection rate under nearly optimal conditions. Passengers on the Diamond Princess cruise ship didn't practice "social distancing." Quite the opposite. Everyone was breathing the same air, touching the same objects, and being in close quarters with everyone else for weeks on end. This data point should have clued us into the fact that this thing doesn't spread all that easily. If it did, most people would've gotten infected.

SARS-CoV-2 will mutate to become more mild but spread more easily

Only in the movies do viruses mutate and become more severe. In reality, the opposite usually occurs: the virus either mutates and becomes less severe (as the H1N1 swine flu did), or it just disappears (like SARS). Community-spread coronaviruses either disappear or turn into the common cold. The same thing is already happening with the SARS-CoV-2 virus. There are two types: S and L. The S type is what blew up in Wuhan and caused havoc. The L type is milder and more prevalent, but spreads more easily, and is already overtaking the S type. As time goes on, the virus will mutate to become more transmissible, but less lethal. This is, quite literally, devolution.

It May Spread More Easily Than the Flu

In the span of 3 months (January 2020 through March 2020), the US has had about 200,000 cases of novel coronavirus. That comes to about 3,000 people per day. Compare that with the number for the flu. According to the CDC, between September 2019 and March 2020, there were over 220,000 positive flu tests in the US. That comes to over 1,200 per day. (And imagine how much higher the flu numbers would be if there weren't a flu vaccine!)

Of course, we need to consider that this isn't an apples-to-apples comparison. The high number of flu cases is due to the fact that flu viruses are always circulating, and anyone with symptoms can get a flu test. With few exceptions, the only people who can get a coronavirus test are those with known contact with a coronavirus patient and symptoms. Consequently, there haven't been nearly as many coronavirus tests as flu tests. This is where looking at the rate of positives can help us. The positive rate is important because it gives us an idea of how much the virus has actually spread, and hence, how contagious it is. The following table contrasts the rate of positive flu tests and coronavirus tests in the US.

Virus Rate of positive tests in the US
Flu viruses 20.5%
Novel coronavirus 17%

Over 80% of people tested were negative for the coronavirus. These are people who came in contact with an infected person and had symptoms. But we have to be careful not to jump to conclusions. The number varies drastically by state, as follows:

State Rate of positive tests
New York 35.7%
New Jersey 39.7%
Washington 7.5%
New Mexico 2.1%

The population density correlates to the rate of positive tests. New York and New Jersey have incredbly high densities. Washington's population density is somewhat lower, and New Mexico's is incredibly low. This makes sense considering that SARS-CoV-2 is a respiratory virus that spreads through coughing and sneezing. This tells us that general quarantines and other drastic measures were overkill, and should be limited to densely populated areas.

Asymptomatic People Aren't Spreading It

Keep in mind that until recently, in order to even get a test, you must have symptoms and have had contact with someone else who tested positive. Some say that if we tested asymptomatic people, the rate of positives would be much higher. But remember that symptomatic people with known contacts are testing positive at a rate of 17% or less in most areas of the country. Therefore, asymptomatic people with known contacts would test positive at an even lower rate.

But for the sake of argument, let's assume that we test asymptomatic people and the number of positives is high, let's say 80%. That would suggest that this virus causes mostly mild illness. And if that were true, the number of symptomatic people testing positive in New York would be much higher than 39.7%. The math tells the story. Asymptomatic people just aren't spreading this virus around.

All this strongly suggests one conclusion: the virus causes mild but noticeable symptoms and spreads easily. And that means quarantines and other isolation measures should be limited to high-risk populations.

We Need Honest Experts

Why all the shutdowns, lockdowns, quarantines, and cancellations? If you listen to the epidemiologists, virologists, and medical doctors, speak on the coronavirus you may notice a particular phrase that they keep using regarding the virus. The phrase is:

"We don't know"

The moment an expert utters the phrase, "I don't know" in regards to a topic, that topic is outside their field of expertise. Because the medical experts don't know where and when the virus will spread, they're erring on the side of extreme caution by suggesting avoiding gathering in groups and staying home if you're in a high-risk group. I believe much of the panic we've seen is due to people failing to making this critical distinction.

The experts' blanket isolation suggestion is not based on evidence, but on the absence of evidence. The experts aren't recommending shutdowns and cancellations because they're necessary. They're recommending them because they believe they're the safest option. Both personally and professionally, there is little downside if they err on the side of caution, but plenty of downside if they don't. We have to remember that the medical experts are scientists, and they will not recommend returning to normal until they have solid data that the danger has passed. That means only after this is over will they say it's safe, and right now, we don't know when that will be.

It sounds strange, but those of us who aren't experts may have to say what the experts are thinking but just can't say. They know how viruses work. They know that the odds of this thing turning into a 1918 Spanish Flu is extremely unlikely. They also know that they can't afford to be wrong. Even a slight error could be career-ending. The experts have a vested interest in not being honest about good news.

Erring on the side of caution is generally wise. But an indefinite shutdown isn't going to work. People are losing jobs, money, and the opportunity to see the people they love and to do the things they enjoy. Life-saving surgeries and treatments are being cancelled. And not even high-risk people can live in perpetual isolation.

We non-experts with no academic or career skin in the game need to look at the data, think carefully about it, and come to a conclusion about when we're going to go outside and play again.

The Curve is Barely a Speedbump

You may have heard the mantra about "flattening the curve". This refers to slowing the spread so that the healthcare system isn't overwhelmed by a surge of new cases requiring critical care. This seemingly soberminded assertion is based on the assumption that this virus will put some sort of an unusual or even unprecedented strain on limited medical resources.

But for the reasons I just laid out, there simply won't be enough cases to strain the medical system across the US. Not even close. And of the cases that occur, most (~80%) won't require hospitalization because they cause only mild symptoms. Right now the curve is barely a speedbump. Of course, don't take my word for it. Try to find a story about US hospitals being overwhelmed with coronavirus patients. The only stories you'll find will be about hospitals that were already under strain even before this virus, particularly in large cities (New York, Seattle, and cities in California).

Better Safe Than Sorry?

The amount of attention on this new coronavirus--particularly of the panic-driven variety--has been like nothing I've seen. The closest I can remember was in the 1990s when everyone was afraid of catching HIV from a toilet seat.

Cancelling large gatherings will save lives regardless of whether there's a pandemic. It will reduce traffic accidents, violent encounters, drunk driving, heart disease, cancer, and a lot of other things. But we don't need a nuclear bomb to kill a cockroach.

If the criteria for cancelling events is that it will reduce some risk, then we can justify cancelling anything at any time. But as we've established, the relative risk of getting this virus is low. And if you're healthy, the risk of serious symptoms is also quite low.

Quarantines work on a small scale. In densely populated countries like Italy, they make sense. In a vast country like the United States, a nationwide suggestion to avoid groups is both unnecessary and unrealistic. Viruses can't rocket through the air over miles. They can only travel as fast as people can. Shutdowns and cancellations should be limited to densely populated areas or areas with populations that are at especially high risk. For instance, a convention for elderly cancer patients is not a good idea right now. But this virus just doesn't spread that easily, so everyone else should go about their daily business, taking all the same precautions that they should normally take during flu season.

Shutdowns should also apply consistently. It makes no sense to close restaurants but keep stores open. Shopping in a store with 50 other people isn't any safer than being at a restaurant with 50 other people.

Viruses Do Discriminate

Thousands of people have died from this virus, so we should take it seriously. And taking it seriously means doing serious thinking, not just reacting. Those with the worst outcomes tend to be older than 50 or have preexisting health conditions, particularly heart or lung conditions, cancer, or diabetes. Some people are born with or develop these conditions through no fault of their own. Others cause or exacerbate their conditions through their behaviors, such as smoking, drinking or eating too much, or promiscuity.

Some countries are healthier than others. China and Italty, which have a high case fatality rate, both have large smoking populations. And in Italy, it's customary to kiss someone when you greet them. As with any respiratory illness, those with reduced lung function, diabetes, cancer, or anything else that suppresses the immune system are at much higher risk. The unhealthier the population, the higher the case fatality rate.

This leads us back to the commonsense advice everyone should have been following all along, and that would have prevented much of the pandemic. Wash your hands. Eat healthy. Don't smoke, drink excessively, or do drugs. Be monogamous. Keep your weight in check.


I'll end this with my predictions:

  • The mass quarantines and isolation ("social distancing") will prove to have been unnecessary.
  • One of the biggest risk factors for death will turn out to be smoking.
  • Many people won't learn from this pandemic. They'll fail to evaluate their own response to it, and will fail to acknowledge that their reaction was disproportionate. Instead, they'll just live in fear of the next virus. But I hope I'm wrong about this one.

Agree or disagree with them, I urge you to do a couple of things. Carefully study the raw data from primary sources (e.g. CDC, WHO, etc.) and think about what it all means. Ignore charts and infographics that don't include a citation. And verify any citations to make sure the pretty picture accurately reflects the data.