On April 1, Toronto public health officials dropped a reality bomb: 12 weeks of “unprecedented” measures would be necessary to contain the COVID-19 pandemic. Medical officer of health Dr. Eileen de Villa used her legal powers to order new restrictions that would continue until late June, and the city cancelled events until June 30.

So what happens next?

Nobody is scheduling a parade for July 1. Asked when life will return to normal, “to give you an exact date, I just can’t tell you right now,” Premier Doug Ford said at Thursday’s press briefing.

Whenever the date does arrive, it won’t herald an instant return to pre-pandemic freedoms, warned Toronto Mayor John Tory.

“It’s not going to be like somebody is going to pull a switch (and) the medical officer of health or the mayor say everything is back to normal right away,” Tory told CP24 on Thursday.

Experts acknowledge, however, that severe restrictions will be extremely difficult to maintain indefinitely. Aside from the brutal economic costs — more than one million jobs were lost in March, according to Statistics Canada — they worry that compliance will dip as fatigue builds.

Neither the city nor the province has released a road map for returning to normalcy, for good reason. It’s too early to say how close Ontario is to the epidemic peak, and leaders at all levels of government are still hammering home the risks of flouting life-saving restrictions on person-to-person contact.

Still, researchers here, and governments in other countries, are contemplating a suite of strategies that might allow those restrictions to ease. Here is what might help, what likely won’t help, and the risks and pitfalls for each.

Hot weather

Let’s clear the bad news first: Despite U.S. President Donald Trump’s earlier assurances that the virus would just “go away” in April when “the heat comes in,” COVID-19 is unlikely to give us a summer break.

Like most of the natural world, infectious diseases do have seasonal cycles. Aside from the obvious winter flu peak, seasonality is a common feature of infectious diseases, including chickenpox (spring), polio (summer), and even sexually transmitted infections like gonorrhea (summer).

Researchers say it’s difficult to distinguish between human behaviours that drive up transmission — children packing into enclosed classrooms during the school year, or a summertime uptick in sexual activity — and the inherent biological cycles of a virus or other pathogen.

But lab experiments on influenza, one of the best-studied infectious diseases, have shown that flu viruses transmit less readily in warm, humid environments than cold, less-humid ones.

Tantalizingly, given the current crisis, the coronaviruses that cause colds also show a marked spike in wintertime transmission and a nosedive in summer. But a warm-weather decrease in transmission of SARS-CoV-2, the coronavirus that causes COVID-19, is unlikely to help us much, researchers say.

Unlike for flu and cold viruses, the vast majority of the population has no immunity to the novel coronavirus. This huge pool of susceptible people is kindling for the pandemic forest fire.

“Seasonality is a main structuring element of our planet,” says Micaela Martinez, a professor at Columbia University’s Mailman School of Public Health. “We can expect that there will be some seasonal features to SARS-CoV-2. It’s just that right now in this pandemic phase, we have such a high fraction of the world’s population that is susceptible, that we can’t expect that seasonal declines in transmission alone will be able to give us this huge drop.”

Any decline we do see shouldn’t dupe us into thinking we beat the pandemic. When Canadian researchers modelled the autumn uptick of swine flu in Alberta during the 2009 H1N1 pandemic, they found that the reopening of schools in fall had a much larger effect on the surge than cold weather did.

“This is a new virus, and we haven’t seen it spread in the summer,” said David Earn, a mathematics professor and member of the Institute for Infectious Disease Research at McMaster University, and a co-author of the Alberta study.

“But based on experience with influenza, it seems very unlikely that weather changes could compensate for social distancing measures.”

Immunity passports

Researchers at Sinai Health and the University of Toronto announced this week that a robotic laboratory platform at the Lunenfeld-Tanenbaum Research Institute (LTRI) has the potential to process 10,000 tests daily that can determine who has antibodies to COVID-19, and potentially some level of immune protection.

The tests are still being fine-tuned, but the ability to carry out antibody testing — also known as serology — on a massive scale is a necessary component for a strategy being contemplated in some European countries: “immunity passports.”

The idea is to identify people carrying antibodies to the novel coronavirus, evidence that their immune system already fought off COVID-19 and they have some level of protection from being reinfected. (These antibody blood tests are different from the typical tests to diagnose the illness, which search for viral genetic material in nose or throat swabs.)

People with protective antibodies might safely return to work, restoring some parts of the labour force.

Not surprisingly, a whack of scientific, policy and ethical questions remain.

Because the virus is still so new, lots of questions persist about immune protection from COVID-19. Are those who already had it completely immune, or merely protected from severe illness but potentially still contagious if reinfected? How long before that immunity wanes? Does everyone produce high levels of antibodies, or just some people?

Secondly, an antibody test that is 99 per cent accurate would still mean that one in 100 people would wrongly believe they are immune, risking their own health and that of others if they did get a “pass” to return to work.

Equity issues are also a challenge. Who gets the test? If it gives some people a “passport” to work and not others, testing would either have to be rolled out across the entire population, or reserved for front-line health workers or those in high-risk settings, like nursing homes and prisons.

Last week, the World Health Organization warned that rapid-result (non-laboratory) immune tests should only be used in research settings, and not for clinical decision-making until more evidence becomes available.

The Sinai-U of T research team is still hard at work, but hopes to tackle some of the big science questions first. The lab is certified for research and would need approval for clinical work, and to expand its industrial partners to massively scale up the production of test kits.

“No test is perfect,” notes Jim Woodgett, Koffler Director of Research at LTRI. But people who test positive for antibodies “can be put into environments where you’re not going to infect other people, and you’re not going to get infected yourself … that does open up possibilities,” particularly for essential services, he said, adding that Germany is already discussing this.

Digital contact tracing

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The bedrock public health tool kit is the same in any outbreak: test, trace, isolate, repeat. No matter how technologically advanced the country, every nation is engaged in confirming new cases through testing, tracing contacts of those cases to hunt down potential new infections, and isolating people to break chains of transmission.

Ontario has been justifiably focused on its failure so far to test widely, a lapse that has assured many cases of COVID-19 are going uncounted and untraced. To fight this pandemic to the bitter end, Dr. Theresa Tam, Canada’s top public health official, said Friday that testing must be scaled up across the country.

Contact tracing has drawn less scrutiny, perhaps because it is more low-tech. Public health staff work phone lines and patients’ memories to track down everyone who might have come in contact with known cases, informing those contacts of their risk and telling them to self-isolate.

A recent study in the prestigious journal Science suggested that manual contact tracing was too slow to catch up to the speed at which the virus is transmitted, and that digital contact tracing — using cellphone location data — would be necessary to stop the pandemic.

Countries in Asia have already used cellphone location data for digital contact tracing and to find patients who are breaking quarantine orders. But in North America, those sensitive to privacy concerns are understandably queasy about sharing an entire population’s real-time cellphone location data with the government: “emergency” powers are sometimes hard to unwind post-emergency.

Yoshua Bengio, a computer scientist at the Université de Montréal, has proposed an artificial intelligence-based app that uses location information and test results to calculate an infectious risk score, but shares that data between phones rather than in a central database.

“The problem is, you don’t want governments or other, for-profit organizations to build a database knowing where everyone was … because it could be abused,” Bengio, a recipient of the Turing Prize and a leader of ethical AI movements, told the Star in March.

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“It can be done completely in a peer-to-peer way. You don’t need to centralize information. If every person has locally the information about the risk they’re carrying, and that information only gets shared with the people they cross,” those concerns can be avoided, Bengio said.

On Friday, arch-rival tech giants Apple and Google announced the creation of an opt-in digital contact tracing tool that uses Bluetooth to notify users if they have been in contact with someone who tests positive for COVID-19, raising a new round of questions about privacy, equity, access and much more.

On-and-off interventions

Epidemiological modellers — the surprise celebrities of this strange new pandemic world — have demonstrated that physical distancing interventions need to continue for months, not weeks, to bring the size of the COVID-19 outbreak down to a size where it won’t sink our health-care system, hastening catastrophic outcomes.

But modellers in Canada and elsewhere have also examined “dynamic” cycling of interventions: pedalling restrictions on and off over an even longer period. The goal would be to keep new cases, hospitalizations and deaths to a minimum, but give everyone intermittent psychological and financial breaks.

A study published this past week in the Canadian Medical Association Journal (CMAJ) found that dynamically cycling interventions in Ontario over a 13-month period would reduce the median attack rate for COVID-19 (the percentage of the population infected) to 2 per cent, would keep ICU capacity from being overwhelmed, and would be more “palatable,” the authors suggested, than a single, fixed-duration intervention.

“In the dynamic scenario, when you release the physical distancing measures, you’re still going to get some amount of transmission in the community,” says Amy Greer, Canada research chair in population disease modelling at the University of Guelph and a co-author on the CMAJ paper. “You are, in more of a controlled way, still allowing some amount of immunity to build up in the population.”

The model used a certain number of ICU admissions for the intervention “on” switch, and Greer said getting that trigger right is crucial — too slow, and we risk another onslaught.

And “ultimately, you would still need to be very cognizant of protecting those at most high risk: individuals who are residents of long-term-care homes,” for example.

The COVID-19 projections released by the Public Health Agency of Canada on Thursday acknowledged a scenario like this, showing a large first wave of the outbreak and subsequent smaller ones.

This strategy — and probably any strategy governments eventually adopt — will likely rely on all of the tools. Testing, contact tracing, and other traditional public health tools will need to be scaled up and sharpened to get a clearer view on exactly where disease hotspots are emerging, and contain them quickly. Immunity testing will help researchers calibrate who is still at risk, and how big the size of the first wave was. A hot weather break, even if it doesn’t save us, can’t hurt.

In the meantime, everybody has to stick with this new, difficult reality.

“If we let up, new chains of transmission will take off in our highly susceptible population and the epidemic will reignite,” Tam said Thursday. “If we are to not lose our hard-won progress, we must stay the course until we have reached a very low number of cases at the bottom of that first wave.”

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