The Canadian Epidemiological summary of Covid-19 cases has a nice graph where they show Covid-19 cases by episode date. They define “Episode date” roughly as when symptoms began rather than the usual when the case was recorded or discovered. They show a shaded region of one week where they say the data is incomplete, which makes sense, because data is still coming in with a lag.

[Edit: significant changes were made on April 3rd which includes an improved16 day uncertainty bar]

At first this made me guardedly optimistic! Were the cases actually possibly peaking? To find out, I went to the WayBack Machine, copied the raw data over time, and created my own graph that colours the cases by the day the data arrived on the website. Using that, we can see how much data is getting updated behind the shaded region. Here’s what it looks like as of late March 31st:

One thing we can say for certain so far is that plenty of data gets updated outside the shaded region. New Covid-19 episodes get added (and shifted around) as far back as about 3 weeks.

So unfortunately the peak showing behind the shaded region is an artifact of the data lag and is not yet reason for optimism about Canadian Covid-19 cases.

Edit: I stopped updating the daily chart which became useless. Check out this weekly chart instead for the numbers. Last updated May 11th and I will not be updating it further because I’m doing this by hand daily so need to either stop or automate it. Here’s a screenshot of the last updated graph below