Canada is smoothing the coronavirus curve. It’s “good news,” says expert – National


Canadians have closed schools and shut down large parts of the economy to deal with the threat of the new coronavirus.

Encouragingly, public health experts say a chart of positive tests shows that the sacrifice works.

“This is a good news graph,” says Steven Hoffman of York University.

“The good news is that it is not a straight line and that it is actually curved downward, which is exactly what we would like to see. These lines do not show that the epidemic is ending. The number of cases could increase. It just doesn’t go up as fast as we expected in the absence of intervention. “

The University of Toronto Ashleigh Tuite agrees.

“Overall, it’s a positive graph,” she says. “All the provinces bend – you want them to be as flat as possible. They are all going in the right direction, which is a positive sign. “

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The chart above will continue to be updated as more data becomes available.

Epidemiologists use charts like this in part to see how long it takes for infections to double – the longer the period, the better.

“It’s just a practical way to think about it: doubling is nothing special,” says Hoffman.

“You can also say how many days it takes before it is 10 times bigger. It’s a useful measure of the pace of what we’re trying to slow down. At this point, our goal is not to stop the spread of an epidemic but to slow down its rate of spread. “

Coronavirus outbreak: Ontario health official says province has “folded the curve” but much remains to be done

Coronavirus outbreak: Ontario health official says province has “folded the curve” but much remains to be done

The graphic below is identical to the graphic above, except for adding reference lines. These lines allow you to compare provincial trends with current doubling rates.

Doubling every other day, the dotted line on the left side of the graph, would be a “very bad sign,” says Hoffman.

“The average we see around the world is four and a half to five days per doubling. If we could bring it down to a doubling every week, it would be better than the rest of the world and would totally change the severity of the epidemic in a very good way. “

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Slowing the epidemic is crucial because it gives the medical system time to cope. If the number of cases becomes unmanageable at one point, doctors are forced to make difficult choices.

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“The scary thing becomes when the curve exceeds the capacity of the system, because that’s when doctors have to start making resource allocation decisions, which are probably among the worst decisions anyone can have. take it, “says Hoffman.

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Urgently, we need to measure coronavirus as a problem, but every way we need to measure it must be considered with an understanding of its faults.

The daily case totals (used in the graphs above) appear to be the most obvious and up-to-date number to examine. However, to measure the magnitude of the problem, these are distorted by the uneven availability of tests and the fact that some provinces test much more than others.

Deaths and hospitalizations are in some ways better, but may reflect infections that occurred three or four weeks ago.

The graph below shows the growth trend of COVID-19 deaths for each province with more than 30 deaths from the disease.

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The numbers are crucial because we have few other tools to answer the questions of life or death, among them: the enormous upheaval caused by the massive closure of the company contributes to slow down the virus, and If so, how? If we were to reopen the economy, how would we know if it was the right decision?

A sharp increase in positive cases could show that the problem is getting worse – or that our knowledge about it is improving.

“Normally, when you test more, you will find more cases,” said Colin Furness of the University of Toronto.

“It would be even better if we tested more and not. All you do is say, “There is an iceberg there.” Part of the iceberg is visible, and we measure it. It doesn’t say anything about the iceberg – it just quantifies what you can already see. ”

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Ontario achieves first COVID-19 test target for coronavirus outbreak, says Premier

If we had the resources, says Tuite, we would ideally test people from a large cross-section of society in a system somewhat similar to that of a juror.

Quebec suffered more than the rest of Canada because of “bad luck,” says Furness.

“They got a super spread, clearly. They received a large dose of people loaded with viruses. Sometimes you only need a few people with a lot of contacts, “he says.

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“Their March break had taken place a week earlier. The time when, across Canada, we started closing schools and so on, it was a week too late for Quebec. If they had just done it a week earlier, and if Ontario had done its work a week earlier – the days count. “

Quebec has also done more extensive testing, says Tuite.

“If you look at the first five days since their 100th confirmed case, they have this very, very rapid growth in cases, and this reflects the fact that in the beginning, they had a very large increase in the tests they were doing in their population. That explains the messy data, ”she says.

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The Maritimes, on the other hand, have had a milder period, at least so far.

“When we look at the Atlantic provinces – New Brunswick, PEI – they haven’t had any bad luck, and partly because they don’t have major international airports, so there is less chance of ‘be unlucky, and they started shutting down stuff when Ontario started shutting down stuff,’ says Furness. “And lo and behold, they are sort of done. The spread never really happened. “

When will the data tell us that we can start lifting the restrictions? All the experts Global News spoke to said that there was no clear standard.

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“The reality is that it will be a trial and error, and I don’t think setting up a schedule is helpful,” said Tuite.

“If you look at how quickly the situation has changed – every week is like a month, or more, in terms of things changing. Our understanding changes where we are in the epidemic curve. “

The graphs above are logarithmic graphs.

In a traditional graph, like the one below, the vertical axis is divided equally: 10, 20, 30. In a logarithmic graph, the vertical axis accelerates by a factor of 10: 10, 100, 1,000, etc. The logarithmic graphs show the change better, but you have to take the distortion into account.

You can see charts like this for dozens of countries here.

Here’s what a more traditional table of known infections looks like:

Click here to view data »

See the link »

© 2020 Global News, a division of Corus Entertainment Inc.


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