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A medical worker performs a mouth swab on a patient to test for Covid-19 coronavirus on Thursday, April 2, 2020.
In late June, doctors at the Toronto General Hospital were still placing near-death people with COVID-19 on ECMO, or extra corporeal membrane oxygen machines, medicine’s most extreme form of life support.
ECMO works by pumping blood outside of the body, oxygenating it and then sending it back in. Calls were still coming in daily from doctors in the Toronto region hurrying to rescue people in “advanced respiratory failure.” Sixty people were transferred to the General; 32 went on ECMO.
“That’s gone away in the last few weeks,” says Dr. Niall Ferguson, head of critical care medicine at Toronto’s University Health Network, who practises at Toronto General. “We’ve seen a dramatic drop off in the number of severe cases in the Toronto region.”
It’s a similar story across the country. As new infections tear across the southern and western United States, setting new daily records for deaths that epidemiologists say were utterly predictable and disastrous, the virus is largely under control in Canada.
Nearly 8,800 lives have been lost, but the daily number of reported case and deaths, the daily numbers of people hospitalized and ICU admissions, have been steadily declining since the peak of the epidemic in April, federal modelling data released this week shows. Transmission rates are tumbling steeply among the oldest, and most vulnerable, with a slower decline among 20- to 39-year-olds. There are hot spots, outbreaks in long-term care homes and among migrant workers, and too many unnerving cases where the source of exposure is a mystery. But otherwise the news is “good,” Canada’s Deputy Chief Public Health Officer Howard Njoo told a media briefing. But relax too much, too soon, he warned, and the epidemic “will most likely rebound with explosive growth as a distinct possibility.”
A second wave is mathematically inevitable, says University of Ottawa epidemiologist Raywat Deonandan. Researchers have only started to get a grip on just how many of us have been exposed, but the majority are still vulnerable. As long as the virus exists in the environment, “it’s going to find purchase and attempt to reassert itself,” Deonandan says. “That’s the way these things work.”
And so comes the quiet anxiety of waiting for the next surge, and wondering, what are our chances of getting seriously sick? How can the SARS-Cov-2 virus cause lethal blood clotting, sudden cardiac collapse or multi-organ failure in some people and not a whisper of a symptom in so many others? How deadly is this really?
It’s too soon to know. The true case fatality rate won’t be known until the end of the pandemic, Deonandan says.
“This infection messes with me,” Toronto infectious disease physician Dr. Jeff Powis tweeted in late June after having called his 700 th patient diagnosed with COVID-19. “Those I expect to do worse do well and those without traditional risk factors get admitted to ICU.”
What increases the risk of death and other bad outcomes? According to a study of more than 17 million people in England published this week in Nature, advanced age, and being male. Diabetes, severe asthma, obesity, chronic heart or liver disease, dementia, reduced kidney function and autoimmune diseases like rheumatoid arthritis, lupus or psoriasis — were also associated with a higher risk of death based on an analysis of the anonymized health records of 17,278,392 adults, slightly less than 11,000 of whom died with COVID-19.
Black and South Asian people were nearly two times more likely to suffer a COVID-related death than white people, for reasons that aren’t fully clear. The most socio-economically deprived were 1.8 times more likely to die than the least deprived, and as Powis noted, health inequities means that, like most infectious diseases, COVID-19 is disproportionately affecting the vulnerable — people living in racialized populations and in poverty, in multigenerational families living in cramped housing, and those with low-paying essential-service jobs and no paid sick leave.
In Canada, people over age 60 make up 96 per cent of deaths. While age and underlying health problems have been identified as risk factors, there are other things at play. The only drug that has so far been shown to keep people from dying from COVID-19 is dexamethasone, a steroid that keeps the body’s immune response from going haywire in response to the virus that causes it. According to preliminary findings published by British researchers in June , the steroid cut deaths in people on ventilators by one-third. “That really points to the fact that it’s our body’s own immune response to the virus that may have a worse effect than the viral infection itself,” says Dr. Mark Downing, an infectious diseases physician at St. Joseph’s Health Centre in Toronto.
Different underlying medical problems might put people at higher risk of a hyper inflammatory immune response, but there’s no test that can predict, “ this is someone who is going to have a runaway immune response his body won’t be able to rein in,” he says.
However, more people in Canada are surviving an ICU admission for COVID-19. In a study of 117 people admitted to one of six ICU’s in Vancouver , 61 per cent survived to be sent home alive at the time study was published. From the original reports out of China, “they were reporting crazy things, like 90 per cent morality for people on ventilators,” Ferguson says. The experience here suggests the prognosis for those who do get critically sick may not be as bleak as the early reports made it out to be. That’s partly because the system was better prepared. Canada’s ICU’s weren’t saturated and stressed to the breaking point. “We were able to rescue patients with ECMO when we needed to,” Ferguson says. Doctors didn’t have to make wrenching decisions over which patients to route to ICU and who to leave behind. Unlike Italy, obstetricians and ear-nose-and-throat specialists weren’t called in to care for the dying in besieged ICU’s.
A greater proportion of cases in Canada are now occurring in younger people, and a smaller in older people. “In some ways that’s unsurprising, because many older people know that they are especially vulnerable and so they’re taking extra precautions,” says Irfan Dhalla, a general internist and a vice-president at Unity Health in Toronto. After a disastrous start, we’re now taking greater precautions with seniors living in long-term care and retirement homes.
But it would be a mistake to think young people are invulnerable from COVID-19. They obviously can get sick and die: Hamilton-born, Tony-nominated Broadway star Nick Cordero died last Sunday at the age of 41. He had been hospitalized for three moths and had a leg amputated. “Just because the fatality rate is incredibly high in people who are in their 80s or 90s does not mean the fatality rate is zero in their 40s, 50s and 60s,” Dhalla said.
So what is the true mortality rate? It’s hard to nail down. In March, the World Health Organization pegged the case fatality rate — the fraction of known cases that die — at 3.6 per cent globally. The case fatality rate is the ratio between the number of confirmed deaths from the virus and the number of confirmed cases, not the actual number of cases or infected people that are floating out around there.
A recent paper in the Canadian Medical Association Journal estimates that, if the reporting rate is less than 50 per cent in Canada, the case fatality rate for COVID-19 is likely to be around 1.6 per cent.
Even then a case fatality rate isn’t constant. It varies with how much we test, with the fragility of the population, and the robustness of our health-care system, Deonandan adds.
The true measure of lethality, he says, is the infection fatality rate — of all the people who get it, whether or not they show symptoms or are even tested, how many will die? Nature reports that a growing number of studies from different regions is pegging the infection fatality rate at between 0.5 and one per cent, meaning five to 10 people will die for every 1,000 infected.
For seasonal flu, it’s 0.1 to 0.2. Not only is COVID deadlier, it’s profoundly more infectious. More people are going to get it. And although some doctors are reporting that the nose swabs being taken now are different from the swabs at the beginning of the pandemic — there seems to be less viral load — to Deonandan that just means we’re testing fewer symptomatic people. Lower the thresholds for who gets tested, and you’re going to get people who are less sick.
“That should not be confused with having a less severe disease present in the community,” Deonandan says.
A pandemic has a way of revealing the nature of a society, he says. “It either exacerbates the disparities or it highlights the strengths.” Canadians, more so than our neighbours to the south, “have embraced this ethic of communal responsibility,” says Deonandan. “For the most part, people are onboard with protecting other people, with wearing masks, with doing what’s right for the community. That’s not a message you see coming out of the USA.”
Other positive signs: Transmission by fomites (contaminated surfaces and objects) doesn’t seem to be as serious as once thought. According to a commentary published last week in the Lancet , most studies used large amounts of virus, higher than what would happen under real-life scenarios. “In my opinion, the chance of transmission through inanimate surfaces is very small, and only in instances where an infected person coughs or sneezes on the surface and someone else touches that surface soon after the cough or sneeze,” within one to two hours, writes Emanuel Goldman, professor of microbiology, biochemistry and molecular genetics at Rutgers University.
Cleaning surfaces is still important, Deonandan says, but perhaps we don’t have to be obsessed with it. The WHO this week acknowledged airborne transmission is a thing, but it’ s not the primary way people get COVID-19. It’s by droplets, and masks diminish droplet transmission, Deonadan says. “It tells me we have the tools to contain this well.”
Dhalla believes so, too. “The overall story I see is that Canada has the resources and expertise to both contain COVID-19 and re-open schools and workplaces at the same time.” That’s provided we keep outbreaks from spinning out of control with well-resourced strategies to test, trace, isolate, support and mask, and hotel rooms for the homeless, or somewhere they could be supported and physically distanced.
Still, it bothers him when people want him to say that COVID-19 isn’t that serious. “I have a hard time with numbers, everybody has a hard time with numbers. It’s hard to get your head around concepts like 0.5 per cent or exponential growth at 1.1 — what do these things mean?
“Ninety-nine-point-five per cent sounds pretty safe. But really, would you take a one-in-200 chance of dying ? I woudn’t. It’s very clear now, four months into the pandemic, that this is a serous illness that has resulted in great loss of life.
Copyright Postmedia Network Inc., 2020