Marking 20 years
of bold journalism,
reader supported.

Switch to a ‘Green Zone’ Strategy for Taming COVID-19

Two physicists believe Canada should aim for zero cases, and lay out how.

Andrew Nikiforuk 24 Nov

Tyee contributing editor Andrew Nikiforuk is an award-winning journalist whose books and articles focus on epidemics, the energy industry, nature and more.

For nine months now COVID-19 has unsettled Canada and most of the world. Millions have suffered from the disease and economies have been upended. Yet no concerted action has been taken in Canada. It’s largely been every province for itself.

“What would it look like if a leader stood up and said, ‘Let’s make an effort together to eliminate this disease'?"

That’s the question two MIT-trained physicists, Yaneer Bar-Yam and Matthias Schneider, are now asking political leaders.

Unlike most politicians these physicists understand pandemics are complex events that require direct, rapid and multi-layered responses.

They also join other experts in arguing that achieving near zero transmission is possible. And much better than living through cycles of exponential growth, lockdowns and renewed waves — Canada’s current predicament.

Or as Yaneer Bar-Yam puts it: “Do it right or keep doing it over.”

Let’s begin with Matthias F. Schneider, who gave a basic talk about the pandemic in his home country of Germany earlier this month. Too bad Canada’s premiers weren’t there.

Eliminating super-spreaders

Schneider began with this truth: "One thing is crystal clear: If you want to stop a fire you do it when it is small, not when the whole city is in flames. You don't need a PhD in physics, medicine or economics to understand that."

His presentation then explained the mechanisms, from power laws to exponential growth, that drive pandemics.

Schneider noted that pandemics are extreme yet highly-probable events with long consequences. Extreme numbers tend to drive these extreme events.

For example about 10 per cent of the population, the so-called super-spreaders, now account for 80 per cent of all infections. Most of these super-spreaders of course, are asymptomatic, and don’t know they are infected.

“Extreme outliers drive the pandemic; not the mass of people,” explained Schneider.

The biggest recorded super-spreader event to date occurred at a soccer game in Milan. That biological bomb infected 7,000 people. But super-spreader events happen every day at pubs, weddings, churches, schools and gyms when super-spreaders breathe, laugh, sing and spit out the virus via droplets and tinier aerosols.

An aerosol is a particle or droplet, about the width of one hair, suspended in the air. These infectious particles can travel much further than six feet (eight metres in one meat plant, research has found). They can also remain suspended in the air for hours.

Just one super-spreader in a pub can launch from 10 to 100,000 aerosols in the air. You only need to inhale about 100 particles to become infected.

That’s why wearing masks is so easy yet so effective. It filters the air both ways. Schneider didn’t mention it but the science on masks is punishing.

U.S jurisdictions such as North and South Dakota, which patently ignored the importance of masks, have suffered horribly in the second wave because they gave super-spreaders a grand advantage.

Schneider said it is almost impossible to predict which people will be super-spreaders, “but we can eliminate super-spreaders by eliminating infections.”

When authorities eliminate infections in a jurisdiction, the community can put a lid on supers-spreading events. But when authorities such as many of Canada’s premiers choose to allow those infections to grow, they act like arsonists in their own homes and feed exponential growth.

The power and damage of infectious surges

Schneider then compared a viral outbreak to a block of ice encountering warm temperatures. The warmer it gets, the more the block melts and then turns to liquid. Physicists call this change a “phase transition.”

In an uninfected human community, mobility works like temperature on a block of ice. As mobility and connectivity increases, more super-spreading events occur, and soon 40 per cent of the community (such as Steinbach, Manitoba) is infected. During a pandemic communities can go from uninfected blocks of ice to infected puddles of water so rapidly that they become totally deluged and everything is put at risk: old folks' homes, hospitals, medical workers and small businesses because everything is connected.

That’s what happened in Manitoba. Authorities played with fire and let the virus get out of control. It then spilled over into Nunavut, which had remained free of the virus until November. Connectivity explains why: People from that territory are dependent on medical care in Manitoba’s hospitals and could not escape the deluge.

How to gauge the danger posed by a COVID-19 surge?

Schneider bids we remember the hospital and death rates that overwhelmed Spain, New York City and northern Italy during the first wave. The first danger is obvious: about 30 to 40 per cent of the total population are at risk for serious complications from COVID-19 due to a variety of health issues ranging from obesity to age, noted Schneider.

Then come the not so obvious long-term risks of infection: pulmonary fibrosis, blood clots, heart inflammation, renal impairment, brain damage, chronic fatigue. In the northern Italian city of Bergamo, where 6,000 people died in the first wave, researchers are now doing a long-term study on the survivors.

Their findings underscore Schneider’s comments. The first group of 750 people examined reported that they hadn’t recovered from their infection even though six months had passed.

Thirty per cent had lung scarring or breathing issues while another 30 per cent had blood clotting problems or heart inflammation. Others complained of fatigue, leg pains and hair loss.

The Green Zone strategy and its advantages

Schneider then talked about the precautionary principle and why it mattered as a basic evolutionary tool for survival.

Risk expert Nassim Taleb once noted that if you encounter a stone and mistake it for gorilla, you might feel foolish but you will survive. But if you encounter a gorilla and mistake it for a stone, you will encounter ruin.

The precautionary principle is simply about “being careful,” said Schneider. His prescription for ending the pandemic’s cycle of surging infections followed by lockdowns and surging infections is the opposite of what most of Canada and Europe is now doing.

First hammer the virus with an effective lockdown and create Green Zones with no infection. Next protect those Green Zones with a multi-layered strategy that Tomas Pueyo calls the “Swiss cheese strategy.”

Each slice of Swiss cheese blocks part of the viral spread. One layer consists of tight borders; another consists of social bubbles; then come masks and proper hygiene and lastly comes testing, tracing and isolation protocols. All four layers have the multiplicative effect of blocking 99 per cent of all infections.

The Green Zone strategy comes from the brain of Yaneer Bar-Yam, another physicist who directs the New England Complex Systems Institute in Boston. He is also the force behind, which believes that Canada could become another Australia or Taiwan by eliminating COVID-19 from its borders.

The website, run by 4,000 volunteers, offers research, advice and graphs on nations that are succeeding and those that are losing.

Bar-Yam is something of an intellectual heavyweight. Having helped to quell Ebola in West Africa in 2014, the scientist understands the complexities of viral outbreaks and the mechanisms driving them.

In 2006 he authored a paper warning that global travel, once it crossed a critical threshold in extreme numbers, “may cross the transition into the realm of pandemics unless preventive actions are taken that either limit global transportation or its impact.”

Unlike most Canadian politicians, Bar-Yam doesn’t think living with COVID-19 is a sustainable idea for people or the economy. But in order to get to zero, politicians have to disregard two prevalent ideologies: “denialism and fatalism.” They also have to respect the importance of speed. During the first wave Greece acted two weeks sooner than Spain. It suffered one per cent of the impact, reported Bar-Yam.

Bar-Yam’s approach calls for three ingredients: patience while everyone takes precautions in a lockdown; good testing and tracing; and isolation protocols followed by a Green Zone strategy where restrictions relax or tighten by geographical regions given the level of viral transmission.

His Green Zone strategy begins with no half-measures but a strong lockdown for four to six weeks.

That includes schools, which Bar-Yam describes as “hubs of transmission.” (One recent study using data from 131 countries found that coronavirus spread surged by 24 per cent within a month of children returning to schools.)

A responsible government must then use that valuable time to identify where the cases are and stop transmission with a massive testing, tracing and isolation program.

“The relaxation of restrictions goes by geographical region, not by business type or profession,” he emphasized in a recent research paper. “This requires restrictions on non-essential travel between zones, so that individuals don’t transfer infections from one zone to another.”

“Opening partway then closing, opening and closing will bankrupt business,” added Bar-Yam in a recent Twitter feed. “Business owners are misled in thinking opening with the virus will benefit them. Entire branches of the economy are being destroyed.”

The Red Zone strategy and its shortcomings

But Ontario, Quebec, the United States and much of Europe have jumped aboard a COVID-19 merry-go-around by adopting a Red Zone strategy instead of a Green Zone one.

But the evidence shows that this common approach feeds a tiring cycle: “Strong actions in COVID hotspots (Red Zones) suppress transmission there. But in other locations transmission continues growing, and then they become Red Zones. It’s a whack-a-mole approach, that doesn’t work,” Bar-Yam has argued.

In fact the difference between a Green Zone and Red Zone approach are startling. “In Red Zone strategy you impose restrictions based on transmission rate, mostly in Red Zones. In Green Zone strategy you start to suppress transmission everywhere, identify, create, open up Green Zones. It is the exit strategy.”

To date only a few countries have chosen this route. They include Australia, New Zealand and Taiwan.

But what they won is precious: Improved health outcomes; reduced pressure on health services and schools; increased social freedom and increased economic freedom along with the promise of a more sustained recovery.  [Tyee]

Read more: Coronavirus

  • Share:

Facts matter. Get The Tyee's in-depth journalism delivered to your inbox for free

Tyee Commenting Guidelines

Comments that violate guidelines risk being deleted, and violations may result in a temporary or permanent user ban. Maintain the spirit of good conversation to stay in the discussion.
*Please note The Tyee is not a forum for spreading misinformation about COVID-19, denying its existence or minimizing its risk to public health.


  • Be thoughtful about how your words may affect the communities you are addressing. Language matters
  • Challenge arguments, not commenters
  • Flag trolls and guideline violations
  • Treat all with respect and curiosity, learn from differences of opinion
  • Verify facts, debunk rumours, point out logical fallacies
  • Add context and background
  • Note typos and reporting blind spots
  • Stay on topic

Do not:

  • Use sexist, classist, racist, homophobic or transphobic language
  • Ridicule, misgender, bully, threaten, name call, troll or wish harm on others
  • Personally attack authors or contributors
  • Spread misinformation or perpetuate conspiracies
  • Libel, defame or publish falsehoods
  • Attempt to guess other commenters’ real-life identities
  • Post links without providing context


The Barometer

Are You Concerned about AI?

Take this week's poll