Explaining and understanding the Coronavirus

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Dr. James Webb

Submitted by Dr. James Webb

There’s a lot of confusion about the current pandemic. It’s confusing because most of the reporters and media outlets covering it don’t have a strong understanding. The terms are used interchangeably and often incorrectly. So it’s difficult for the general public to keep track. I think the best source right now to understand it for a layperson is probably this WHO page.

COVID-19 is the name of the actual disease (by WHO). Two important concepts about infectious diseases are 1) how good are they at spreading and 2) how good are they at killing the host. A ‘successful’ virus or bacteria doesn’t kill the patient (host) before the host can spread it to others. If a person dies from a virus before they spread it to others, it can be deadly but contained (like Ebola). If it spreads well but doesn’t kill many people it infects, then you have a more ‘successful’ pathogen, for example, the cold virus.

The current pandemic disease is called COVID-19 but the virus causing it was initially called 2019-nCoV until it was found to be genetically related to the SARS virus (both are Coronaviruses—more below). Now the virus is called SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). This chain of events and naming causes a lot of confusion. If you want to read more about the actual naming, check out this article in Nature.

PathogenDisease Caused by Virus
SARS-CoVSARS
SARS-CoV-2COVID-19
Rabies virusRabies
PoliovirusPolio
HIV-1, HIV-2AIDS

There are now 7 known coronaviruses that affect humans. 4 are common ‘cold’ viruses. The other three are more recent cross-species cross-overs, namely the current SARS-CoV-2, the SARS-CoV (that caused “SARS”) and MERS-CoV. More on that here.

It’s important to understand that the disease COVID-19 is not the same as SARS because they are caused by two different viruses. SARS-CoV and SARS-CoV-2). It’s a different but genetically related virus. What makes this a new strain is that the genetic material (in the case of Coronaviruses it’s RNA, not DNA) is a different virus. As such, the two viruses have different RNA sequences. Viruses evolve through mutations. At some point back up the evolutionary tree, there was a common virus that both SARS-CoV (SARS) and SARS-CoV-2 (COVID-19) came from, but we haven’t discovered it yet and may never.

SYMPTOMS

There is confusion about COVID-19 and if it’s just a cold. This confusion persists because symptoms of most respiratory viruses are very similar.

I’ve been asked if COVID-19 “always goes to the lungs?” The disease, COVID-19, affects different people differently. Most people who get COVID-19 (caused by SARS-CoV2) will only have mild symptoms. But about 20% will have symptoms severe enough to require hospital care. Those generally will have a more severe infection causing difficulty with breathing and/or pneumonia. Of those patients that require hospital care, some may need a mechanical ventilator.

It’s common for folks to get a viral upper respiratory infection and then get bacterial pneumonia (lower respiratory infection) on top of that. Many different viruses can cause people to get secondary bacterial pneumonia. That’s called a ‘secondary infection’ because it’s a separate, second and distinct infection. What usually happens is gunk drops down the back of the throat down the windpipe and into the lungs. That’s commonly called “post-nasal drip” and can even occur with allergies and no infection. If you can cough it up and your immune system can beat the infection great; otherwise you may end up with pneumonia.

The point is that while not every virus can cause viral pneumonia, essentially any viral or bacterial respiratory infection can lead to bacterial pneumonia. The most common reason that a virus causes pneumonia in one person and not another is if the former is either a current smoker or has another underlying medical condition.

MORTALITY (How deadly is it?)

So far today as of 3/15/2020, we have about 163k confirmed cases worldwide with a little over 6k deaths. The death rate looks like 3-4%, but it is very likely that many people with the virus are not getting tested, especially in the US. Experts are estimating the kill rate is probably 1-2%, but we won’t know until later.

Today was an important day because it’s the first time that there were more infections documented outside of China than in China. The virus is spreading globally. The new epicenter is Europe. Many speculate that US numbers are artificially low because many, if not most, people with symptoms in the US aren’t being tested.

What we do know is that this virus is less deadly than SARS, but it definitely spreads easier. So why the kill rate of the disease COVID-19 is lower than SARS, it’s killed way more people in total because it’s infected over twenty times the number of people that SARS did so far. SARS only infected about 8,000 people worldwide but killed close to 10% of those infected (about 800).

Another question…“What is making this a pandemic when SARS wasn’t?”
A pandemic is a disease that is running rampant across the globe and not just isolated to a particular area (epidemic). Basically it’s epidemics all over the world. This is a pandemic because it’s a true global infection. SARS was restricted mostly to Asia, MERS to the Middle East.

That’s one answer, but the real reason the disease COVID-19 has become a pandemic is because the virus, SARS-CoV-2, is much better at spreading than SARS—and again, SARS was caused by SARS-CoV.

WHAT’S GOING TO HAPPEN?

We can’t know for sure what’s going to happen, but we can guess. Currently, the number of newly diagnosed cases outside of China is doubling about every 4-5 days and currently stands at about 81k. That means unless things change we are likely to go from 81k cases worldwide to over 2.5M within a month, approaching 100M in two months. That’s unlikely to keep spreading so quickly given the drastic measures we are undertaking including restricting travel, but it could happen.

What’s more important to ask is what would happen if the worst-case scenario occurs? The vast majority will recover. Chances are if you’re reading this, you’ll survive with not much more than a cold. You’re not going to turn into a zombie. We’re already seeing the worst of humanity in herd mentality with mobs buying toilet paper and acting like wild animals—the vast majority of those people will survive even if 3 billion people end up getting infected.

Those who should be more concerned are those over 65 or who have other medical conditions such as emphysema, diabetes, etc. If you or a loved one falls in that category, I would recommend self-quarantining to protect yourself. If it’s easy for you to self-quarantine then do that now. There are some indications that the virus can be spread by asymptomatic carriers. You should be concerned but not afraid. Do what you can to avoid exposure now. Try to stay away from large groups. Don’t go on vacation with your grandkids for spring break. Just don’t panic. In all likelihood, you’re going to be fine.

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