Contigion: Cheatham County edition

Unfortunately, it looks like the COVID-19 virus plaguing China is here to stay, and my assumption is that it will eventually make its way here to the US.   So I wanted to go over some basic info on the virus. I will be updating this page going forward as long as it makes sense to do so.

  • When can we expect a vaccine/cure?

It is expected to take 18-24 months to generate enough vaccinations to inoculate the general public. Though that depends on a) the vaccine passing clinical trials without encountering major problems and b) if a vaccine *can* be created.   We’ve been trying to develop an AIDS vaccine for 3 decades, as well as vaccines for several other viruses without success.   So a vaccine is not a given, and even if we can make one, it might conceivably take years/decades.

And while scientists are testing various drugs on patients to see if any are effective, they haven’t announced any “silver bullets” yet (though there are a few including chloroquine, an antimalarial drug, that are showing good results in initial testing).

So for the foreseeable future, public health measures are our best and likely *only* way of stopping the spread of the virus.

  • What is the fatality rate of the virus?

The virus appears to hit three groups especially hard: a) Older people, b) men, and c) smokers and former smokers. Obviously, the more of those risk factors you have, the more susceptible you are going to be to it.

Click here for the Johns Hopkins dashboard on the virus.   The numbers on this page will be used for the formulas below.

There are two ways of calculating the fatality rate: dividing deaths by confirmed cases (which tends to *underestimate* the mortality rate), and deaths / (deaths + recovered), which tends to *overestimate* it).

The Chinese government and WHO have been using the first measure.

Fatality Rate = deaths / confirmed cases = 2,466 / 78,891 = 3.1%

However, this measure is flawed in several ways. The most important is that many people who are confirmed to have the virus are fairly new, and thus haven’t had time to become seriously ill. If someone has had the virus for a week, you can’t really say they’ve survived until several weeks later, as many patients have relapsed or died suddenly weeks after their initial infection.

By the other measure:

Fatality Rate = deaths / (deaths + recovered) = 2,466 / (2,466 + 23,386) = 9.5%.

Which is significantly higher. This number tends to *overestimate* the fatality rate because a) the Chinese appear to be especially susceptible to the virus due to their extreme pollution weakening their lungs, b) it can’t count cases where the person is infected but doesn’t get sick, and c) we are likely to get better at fighting the disease as time passes.

By comparison, the seasonal flu has a 0.1% mortality rate.  So by conservatives estimates this virus is between 31 and 95 times more deadly than the seasonal flu.   And while I hope further data sharply decrease this number, this is where we are right now.

This is *not* a virus you want to take chances with.

  • What is the transmission rate?

The official R0 (reproduction number) of the virus was estimated to be ~2.3, as many viruses in the coronavirus family have a similar transmission rate. Which means that every person carrying the virus will infect another 2.3 people on average.

Newer research suggests that the reproduction number is even higher (3.25 ≤ R0 ≤ 3.4). Which is huge, even if it doesn’t sound like it.

If the 1st patient infects 2.3 other people, then after 10 rounds there are 4,142 infected people. If the 1st patient infects 3.4 other people, then after 10 rounds there are 206,428 infected people, almost 50 times as many. So small differences in R0 can have *huge* implications as to how easily the virus is spread and how many people get sick.

The size of R0 also has important implications on how to stop the virus. We don’t need *everyone* to be immunized in order to stop the virus. There is something called “herd immunity”, which means that if a critical percentage of the population is immunized, the virus will no longer be able to spread and will die out.

The critical percentage is (1 – 1/R0). Using an R0 of 2.3, that implies 56.5% of the population has to be immunized before the virus will die off. Using a R0 of 3.4 implies 70.6% of the population will have to be immunized. This is not good, as only 45.6% of people get their annual flu vaccine, so reaching a higher vaccination rate is going to be difficult and will likely require mandatory vaccinations.  Antivaxxers are likely to get a lot of people hurt if they resist.

  • What will happen in the US if the virus gets here?

From reading some CDC papers, their most likely response to the virus is likely to be 1-3 weeks of “snow days”, people voluntarily staying home in order to short-circuit the virus’s transmission, with the additional hope that we get an early warm spring that helps bottle up the virus until fall.

On the assumption that “snows days” are in our future, here are some essential preparations:

  • 3 weeks worth of food for your family. If you’re a typical American, you probably already have this, but it’s worth double-checking.   More probably wouldn’t hurt.
  • 3 weeks worth of food/supplies for your pets.   Also medicines, litter, etc.
  • 3 weeks worth of drinking water. For most people tap water is fine, but you may want to have some bottled water as well in case there’s problems with tap water.
  • Refills of any crucial prescriptions you may have. A large number of pharmaceuticals are made in China, so there is a growing likelihood of shortages in coming weeks.
  • Cleaning supplies. Soap, cleaning wipes, alcohol gel or rubbing alcohol, peroxide, white vinegar, trash bags, toilet paper, paper towels.
  • Entertainment. It’s crucial both for yourself and for the general public that you stay at home for the full quarantine period, so find ways of keeping yourself occupied so you don’t get cabin fever. Buy that book you wanted to read, splurge on some movies, etc. Whatever works for you.

Since the entire purpose of home quarantine is “not leaving your home”, the above should suffice for most people. But there are folks who have to leave their home, either because they have critical jobs or they experience an emergency of some sort. In that event:

  • Wear a face mask. A N95 or higher is optimal, but *any* mask will somewhat reduce chances of being infected. Face masks need to be replaced every 2 hours to maintain effectiveness. If you don’t have a face mask, wear a bandanna or shirt wrapped around your mouth. This will offer some marginal protection, though admittedly not much.
  • Eye goggles or a face shield. The virus can be transmitted if viral particles contact your eye.
  • Have a quarantine room in your home, so you can enter/leave without endangering anyone else. A garage makes a very useful one.  Take your clothes off before entering the home and leave them there if possible, and clean yourself and anything you have touched extremely thoroughly with soap and water. Once done, if you have the time to do so, wait in the quarantine room for a few hours, to further reduce the chances of transmitting any residual virus.
  • Viruses in general prefer cold, dry air, which is why colds/influenza primarily occur in the winter. If you can, heat your house or at least one room as warm as you can comfortably tolerate, and have a humidifier, tea kettle, or boiling water on the stove going to increase the humidity of the space.   Note that this isn’t going to “magically” sterilize an infected room, it just reduces the virus’s ability to survive on surfaces over time.
  • Keep your hands in your pockets whenever possible. The virus can be transmitted by touch, and humans touch their faces all the time without realizing it. The easiest way to avoid touching potentially infected items and then touching yourself is to keep your hands in your pockets whenever you can.
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