Saturday, 16 May 2020

Ontario's Covid 19 Progress to Date: Not Quite There Yet

As of May 16th, 2020 Ontario is reporting 22,313 confirmed cases of Covid-19 and 1,858 deaths.  The good news is that 75 percent of cases are resolved and the active number of cases is trending down.  There have been some data glitches in reporting the last few days and while the number of new cases is trending down, it remains that the number of new cases is still what I would term a smouldering burn with the potential for re-ignition.  This is of course a concern given that Ontario is beginning to resume activity with an acceleration of openings on Tuesday.

To be fair, this is a disease whose transmission can be prevented by avoiding crowds and long-term presence in confined spaces, spending more time in outdoor well ventilated areas, practicing social distancing and practicing good hand hygiene. At the same time, this requires a fair amount of self-discipline and given that our daily case numbers are still bouncing between 300 and 400 for a week now, it means a chunk of the population still believes the rules do not apply to them and do not understand the concept of negative externalities.  These are probably the same types of people who let their barking dogs out in the middle of the night or throw cigarette butts and fast food wrappers out the window as they drive.

The figure below shows the number of daily cases with a LOWESS smoothing trend fitted for the period January 25th to May 16th.  The trend shows the number of daily cases peaked on Day 92 - circa April 25th - have have been trending downward since but the decline has been slowing and there may even be a slight upward tick.



Of course, it is not the number of new cases per day but the growth rate of total cases that is even more important and the goal should be to get it below 1 percent (and ultimately zero).  Italy, for example, is now seeing the growth rate of its total Covid-19 confirmed cases at about 0.4 percent.  But then despite initial stumbles, it has been following a stricter lock-down because it was hit much harder than other places.  Why is 1 percent important?  Well, at one percent growth it would take 72 days for the total number of cases to double.  At 20 percent daily growth - which was where Ontario was in late March - the total number of cases would double in just over three days.  If you want to get the pandemic under full control and have new cases not reignite a major spike that overwhelms the health care system, then you need that growth rate below 1 percent.  Ontario at present has seen the growth rate fall below 2 percent but the last few days have not seen it below 1.5 percent.  That is not good enough.

Ontario also appears to have a number of distinct regional pandemics under way as the next figure illustrates.  When the cases are sorted by public health units in terms of total confirmed cases per million and a two-unit moving average applied, here is what the picture looks like.
 

The highest rates of infection have been in Toronto and  Peel at 3,023 and 2,466 cases per million respectively.  There is then a drop off to a second tier in terms of severity and these health unit areas are Leeds-Grenville & Lanark (Eastern Ontario), Windsor-Essex, Durham. Ottawa, Haldimand-Norfolk, Waterloo, York and Lambton and they range from a high of 1,932 to a low of 1,713.  There is then another drop-off to a third tier consisting of the remainder going from a high of 1,291 cases per million in Niagara Region to a low of 150 cases per million in Algoma.  Note, that some of these regions are nowhere near 1 million people in population.  Thunder Bay District, for example, clocks in at 520 cases per million population but there are only about 140,000 people in the District so do the math and you can see the absolute numbers are quite small.

So, what is the long and short of this?  To date, the province has been pursuing a one-size fits all policy in dealing with the epidemic which was fine in dealing with the start of the first phases of the pandemic. However,  a one size fits all policy for re-opening given that some people are already slacking off on precautions is a bit of a concern especially in the parts of the province with higher case densities.  So, if we are going to open things up up at the same rate everywhere, everyone everywhere needs to continue exhibiting common sense and exercising personal caution and distancing measures.