R0: Why COVID-19 is As Good as Dead

But We Must All Do Our Part to Make it Happen

While nothing in this article constitutes formal engineering (or medical) advice, the coronavirus is as good as dead in the United States. This does not mean it is dead yet, or that it is not a deadly danger; the end is however in sight even in the absence of a vaccine or antiviral treatment. The other piece of good news is that COVID-19 is likely to take the seasonal flu down with it when it goes.

It's As Simple as RO, the Basic Reproductive Rate

The reason consists of the very simple R0, or reproductive rate, from epidemiology. This article from the Washington Post puts it in perspective. It is the average number of people to whom an infected individual will transmit a disease. Smallpox, with an R0 of 5 to 7, was particularly terrifying because anybody who had it would give it to several other people, and it had a relatively high lethality rate. Measles is incredibly contagious, and its recent resurgence is a good reason to get the MMR (Measles, Mumps, Rubella) vaccine which I have done. Vaccines have largely put an end to highly contagious diseases like smallpox, measles, mumps, and also polio, but there is currently no vaccine for COVID-19. This does not mean it cannot be stopped, and the way to do that is to get its basic reproduction rate below 1. This we are already doing.

Wikipedia cites four references to get an R0 of 1.4 to 3.9, which is somewhat worse than the 2.0 of the 1918 Spanish flu epidemic. The exact value, which is yet unknown, isn't important. All we need to do is get it below 1 to get COVID-19 to burn itself out and take the seasonal flu with it.

Suppose for example the R0 of COVID-19 is 3.0. This means that anybody who gets it will give it to, on average, three other people via one or more of the following transmission routes:

1. Coughing or sneezing to expel infectious droplets; the effective range is roughly six feet. This is why people who have COVID-19 should wear masks to protect other people.
2. Depositing infectious liquid (e.g. from sneezing, or from the hands) on a surface that is then touched by somebody else, such as a doorknob or a shopping cart. One can similarly get it by touching a contaminated surface, and then touching one's face; a habit that is very hard to break.
3. Shaking hands, an old custom our society is now rethinking

The fact that people have largely cleaned stores out of hand sanitizer (along with rubbing alcohol and even hydrogen peroxide), and a lot more attention is being given to hand hygiene in general, suggests that the principal transmission routes for not only COVID-19 but also the seasonal flu are already being shut down. Other actions, such as sanitization of frequently-touched surfaces like touch screens and shopping carts in stores, also are being taken. I now use disposable gloves while shopping. I also use the sanitizing wipe on the cart or basket if one is available, which is now almost universally the case, and I keep a bottle of hand sanitizer handy as well. Public gatherings and school classes are being cancelled in favor of distance education, as COVID-19 is unlikely to figure out how infect somebody via the Internet rather than face-to-face contact.

These countermeasures do not have to prevent every single case of COVID-19; all they need to do is get its basic reproductive ratio below 1.0 to make it history by summer even if an actual vaccine is not available until 2021. They are also likely to reduce the R0 for seasonal flu to less than 1.0 which is also good as this year's vaccine did not apparently cover all the bases. "...the overall estimated effectiveness of seasonal influenza vaccine for preventing medically attended, laboratory-confirmed influenza virus infection was 45%."

Eternal Vigilance is the Price of Public Health

Even after COVID-19 is defeated, we can never let our collective guard down again lest it return, or anything like it take its place. Hand hygiene should become an almost unconscious part of the way we do things, and thought should be given to virtual conferencing and remote attendance options for sporting and cultural events. Door knobs are infamous for spreading bacteria but antibacterial door handles are available. I do not know if copper is also effective against viruses but Dortrend sells a coating that also destroys viruses. The bottom line is that soap, a centuries-old invention, is our best friend and we should use as much as we can.

The countermeasures we are now taking should meanwhile relegate the seasonal flu to a relatively rare disease as opposed to an annual menace that kills tens of thousands of people annually. We need to continue them even if COVID-19 somehow magically vanished tomorrow.