Treat this pandemic like a chain reaction | Column
There’s one way to control a nuclear reaction; it works for the coronavirus, too, write two scientists.
Nurse Kathe Olmstead, right, gave volunteer Melissa Harting, of Harpersville, N.Y., an injection as the world's biggest study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., got under way this summer.
Nurse Kathe Olmstead, right, gave volunteer Melissa Harting, of Harpersville, N.Y., an injection as the world's biggest study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., got under way this summer. [ HANS PENNINK | AP ]
Published Sep. 5, 2020

President Donald Trump demanded that the United States reopen for business. Red state governors rushed to obey. Sick of months of lockdown, Americans were desperate for normality. They rushed to beaches, bars and restaurants. Sixty thousand and more new cases every day. Trump says COVID-19 will disappear.

Peter Zimmerman
Peter Zimmerman [ Courtesy of Peter Zimmerman ]

It won’t. Throughout much of the summer 2020, more than 1,000 Americans died every day of COVID-19. The death rate is down somewhat today, but there is no guarantee that the change is permanent. If the policies advocated by Gov. Ron DeSantis and his adviser, Dr. Scott Atlas, are followed, we will have another case explosion this fall.

Atlas argues for testing only sick people to confirm a COVID-19 diagnosis. This is exactly backward. We do not test to diagnose cases; we test to find otherwise undetected cases of the disease. In the last six months of fighting the pandemic, scientists have learned that COVID-19 is often spread by people who are asymptomatic, people who have the virus but show no signs of the disease. But those are precisely the patients we must find and isolate in order to protect all of us — particularly the most vulnerable.

John E. Connett
John E. Connett [ Provided ]

Without an effective vaccine or a reliable therapy, there is only one way to treat the pandemic, and that’s the same way our ancestors handled the medieval Black Plague and the 1918-1919 flu. It’s Epidemiology 101: Find those who are infected, trace the contacts of those who were exposed, quarantine them. And so on. But now the Centers for Disease Control and Prevention (CDC) and DeSantis, at Trump’s behest, have recommended cutting back testing of symptom-free people.

One of us (Peter) is a physicist, not an epidemiologist, with expertise in nuclear chain reactions. The other of us (John) is an investigator in two clinical trials of drugs to treat and prevent COVID-19. It turns out that the mathematics of epidemiology are strikingly similar to those of a nuclear chain reaction. The evolution of an epidemic is very similar to firing up a nuclear reactor. One neutron strikes a uranium nucleus, which gives two more neutrons, which split two more atoms, which yields four neutrons and so on.

One person coughs; two more people get the coronavirus. Each of them infects two more victims, meaning four cases. Then eight, sixteen, 32 ... To slow a nuclear reactor, we insert control rods to absorb some neutrons. To slow an epidemic, we space people farther apart. An infected victim must travel farther to infect somebody else. If he self-quarantines before finding a new victim, the epidemic terminates. Alternatively, if a victim refuses to wear a mask and goes to a bar, he can become a super spreader..

The epidemic explodes.

Nuclear engineers speak of the k-factor; epidemiologists speak of the R factor. The two are similar. If R (the expected number of new infections caused by each newly diagnosed victim) is greater than 1.0, the pandemic attacks more and more people. If it is less than 1.0, the disease dies out. Social distancing decreases R. Quarantines bend the curve sharply toward R less than 1. The wise actions of individual governors and mayors made that happen.

With the economy crashing, however, President Trump forced a rapid reopening of exactly the places where people congregate and spread the virus. The president disparaged the wearing of masks, which pushed R still higher. It is now around 2.5, about like the k-factor in an atomic bomb.

A single neutron is enough to set off a nuclear bomb; a single new victim allowed to spread COVID-19 is enough to transform an area where the virus is under control into one where the disease is running wild. We almost had this pandemic under control in May and June, but relaxing social restrictions was like pulling out the control rods from a reactor and letting loose a biological Chernobyl.

As long as the virus is around and as long as vulnerable people can cross paths with it, we are in trouble. Don’t listen to anybody who says we are not. The United States has not been faced with a pandemic of this magnitude since the 1918-1919 influenza. Nobody living has had to combat something like this. However, in 2001 the United States, and specifically the U.S. Senate, was attacked with a historically deadly disease, anthrax, spread by a terrorist. Then-Sen. Joe Biden helped organize the Senate’s response. His first proposal: Establish a global emerging disease surveillance network. His second: Distribute N95 masks to every American in areas at risk. For around $1 per person, even a widespread anthrax attack would have been brought to a halt.

How can we tell we are winning this war?

COVID-19 has an incubation period of about five days, and after symptoms develop it typically takes about another 14 days until the victim either recovers or dies. In round numbers, that’s 20 days. Infected people can spread the disease almost that whole time. Because symptom-free victims can transmit COVID-19, just going three weeks without seeing new cases is no guarantee that it isn’t hiding in some dark corner. A random sample of symptom-free people must be tested routinely. Any new cases mean the bug is lurking, seeking human prey. Even one case could start a new explosion.

If an effective vaccine is found or if testing becomes widespread, random and fast, things may improve. A vaccine could drive R below 1.0. Until then, “no new cases” means none. If a new case appears, the clock starts over again because COVID-19 is still alive somewhere. We will have to take some steps to reopen the economy before a vaccine is available and before we reach absolutely zero new cases. But newly infected victims must be quarantined, their contacts traced and tested, and any found to have the virus must be isolated and still more contacts traced. And so on, until no new infections are found. We agree that it will be hard. But opening the floodgates earlier, as we saw in July, was a disaster.

Other countries have figured this out. Why can’t the United States learn from them? COVID-19 must be truly beaten before we declare victory and return to normal.

The reopening of American society must be tightly coupled to testing, tracing, mask wearing, hand washing and quarantine. Without this, we may see as many as 250,000 COVID-19 deaths before Election Day. There is no shortcut to safety. No new cases means just that. Read our lips!

Peter D. Zimmerman is emeritus professor of science and security in the War Studies Department of King’s College, London and the former chief scientist of the U.S. Senate Committee on Foreign Relations as well as a former science adviser for arms control in the U.S. State Department. He is a fellow of the American Physical Society. John E. Connett is professor of biostatistics at the University of Minnesota. He has a doctorate in mathematics from the University of Maryland. He was head of biostatistics at Minnesota, 2001-2010. His expertise is in large multi-center clinical trials. He is currently an investigator in two Minnesota-based clinical trials of drug therapy to prevent and treat COVID-19. They wrote this exclusively for the Tampa Bay Times.