In some countries, most notably Italy, Spain, and the United States, confirmed COVID-19 cases are exploding and overcoming the ability of the infrastructure to care for the afflicted. In others, such as China and South Korea, the number of new cases has either been reduced to a trickle, or never took off in the first place. What’s the difference? What are China and South Korea doing that Italy, Spain, and the United States are not?

The answer to that question has to do with a mathematical quantity named R₀ (R-naught), the basic reproduction number of an infection. R₀ depends on the intrinsic infectivity of a pathogen and on external factors, such as how people behave. If, for example, a disease has an R₀ of one (R₀=1), it means that, on average, an infected person passes on the infection to one other person before reaching an endpoint. When R₀ is 1, the infection persists but does not grow or shrink. The endpoint is either death or recovery. Once a person reaches one or the other of those endpoints, they are no longer infectious.

Some infected people will not pass the disease on to anyone else before reaching an endpoint. They have an R₀ of zero. Others may pass the disease on the several people, and some (super spreaders) can pass the disease on to many people. Any situation where people are close to each other, such as on a bus, on a cruise ship, in a stadium, or in a church, is a recipe for super spreading.

Once an epidemic has taken off, as the COVID-19 pandemic has, what must be done? The answer is simple, but achieving it is not. On average, R₀ must be driven below 1. Once that happens, the pandemic will eventually fizzle out. This is what has already happened in Wuhan, China where this all began, and has also happened in South Korea, where a super spreader in a church infected a lot of people. Both China and South Korea instituted strict (some say draconian) rules and their populations complied with them. This drove R₀ below 1 and now those two countries are returning to normal while much of the rest of the world moves into crisis mode. This is particularly true of the USA, where the rate of new confirmed cases is jumping higher and higher every day. The case load in the United States zoomed past Spain, then Italy, and then China, to become the COVID-19 capitol of the world.

There is no vaccine for COVID-19 and there are no drugs or other treatments that have been shown to be both effective and safe against it. The only weapon we have is social distancing. Surprisingly, social distancing is quite an effective weapon. If you don’t get close enough to an infected person to be infected by a cough or a touch, you should be safe. You also don’t want to touch any surface or object that has been touched or coughed on by an infected person. If you do, apply disinfectant to your hands or wash them right away. Disinfect any possibly contaminated surfaces or items. Wash your hands and disinfect your mail after you retrieve it from your mailbox. Hopefully your letter carrier is not infected, but that’s not guaranteed. People with COVID-19 become highly infectious before they show any symptoms of the disease. By the time they show symptoms and isolate themselves, they may have already touched the latch on hundreds of mailboxes.

The advice being given by scientists in the know, is your best chance to stay healthy.

• Stay home
• If you go out, stay at least six feet away from anybody you come across.
• Wash your hands when you return home.
• Don’t touch your face with your hands.
• Don’t cough into the air. Cough into the crook of your elbow instead.

Be well. Stay home.

BIO:

Allen G. Taylor is a 40-year veteran of the computer industry and the author of over 40 books, including Develop Microsoft HoloLens Apps Now, Get Fit with Apple Watch, Cruise for Free, SQL For Dummies, 9th Edition, Crystal Reports 2008 For Dummies, Database Development For Dummies, Access Power Programming with VBA, and SQL All-In-One For Dummies, Third Edition. He lectures internationally on astronomy, databases, innovation, and entrepreneurship. He also teaches database development and Crystal Reports through a leading online education provider. For the latest news on Allen’s activities, check out his blog at wwwallengtaylor.com or contact him at allen.taylor@ieee.org.