Thread trying to make sense out of why we still don't have the covid alert app in BC. Yesterday the PHO said that the app in the current form is not useful to augment contact tracing in BC, speaking about this starting at 39:35
The key point seems to be that the covid alert app is designed for maximal privacy, which comes with tradeoffs as to how much information people notified of an exposure and by extension PHO get. In particular the APP is designed so that users won't know when the exposure occurred
In practice this means the app is casting a wide net. Anyone that came into "close contact" with an infected person over the 14 days prior will get notified, even though the infected person likely wasn't infectious for the entire 14 day period.
The reason for this is that the app is designed so that health care workers can't link the exposure keys of the infected person to the infected person, so they can't filter the exposure keys to the likely infectious period.
Ontario deals with this by testing and reverse contact tracing everyone who received an exposure notification (and contacts public health), and then advises to either self-isolate (positive test), or self-isolate or self-monitor (negative test) depending on the risk assessment.
That's not perfect, but seems like a good and useful protocol, taking the privacy level fixed. The BC PHO doesn't agree and wants a more invasive contact tracing app that allows the linking of infected individuals to their exposure keys so that they can be filtered.
The privacy tradeoffs are directly connected with people's willingness to use the app. Over 30% of Canadians have stated that they are unlikely to use a contact tracing app, and off those privacy was the main concern.…
As background, BCCDC has in the past pushed for a maximally invasive location tracking app, showing little appreciation for people's privacy concerns. This may explain why they are so averse to working with high user privacy app.
Anyway, to me this standoff appears to be driven by BC being uncomfortable with casting a wide net, and having less direct information, when contact tracing. The app could indeed be designed differently, e.g. in Germany people will know what day they have been exposed.
The question is not if the app should or should not expose more private information, it's if the app as it is now is a net plus for BC. I strongly believe it is. Could it be better? Maybe, but that can also be fixed after adopting the current app and is no reason to wait.

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More from @vb_jens

17 Oct
Folding in today's data release BC looks like it's on a clear upward trajectory again. This is not good. The time for coordinated counter measures was probably two months ago, but better late than never. This train is moving in the wrong direction and need to get off.
Fraser is driving this trend, and we might want to think about a regionally differentiated response. But it's not clear to me that the boundaries between Fraser and Vancouver Coastal at that meaningful, looking at finer geographies would make it easier to tailor the response.
For comparison, people in SK are worried about their 7 day incidence reaching 5 cases per 100k in the near future. From BC's perspective those numbers sounds really nice, Fraser is at 33 right now and Vancouver Coastal is at 25.
Read 4 tweets
16 Oct
Catching up with yesterday's press briefing, some of the answers of the PHO are disappointing. On including private tests: "some of those are included", "even without those our testing rates remain low". What are the rates? How many are "some"?
And why has the PHO, week after week, been pointing to positivity rates that include private routine asymptomatic testing as evidence that we are doing well when they now nonchalantly point out that this (of course) skews the positivity rate.
The blurring of lines between routine asymptomatic testing with asymptomatic testing in response to an exposure event is also very unhelpful. The PHO must understand the difference, and blurring the line between these is distracting from prioritizing effective TTI strategies.
Read 10 tweets
9 Oct
The question why Canada learned so little from its SARS experience is interesting. After all, much of the success of Taiwan fighting Covid-19 is due to their action plan developed in response to SARS.…
The senior advisor to the original SARS report has written a follow up looking at where things broke down in the Canadian covid-19 response, focusing on failures to protect health care workers and how Canada mismanaged the response.
The whole report is worth a close read, but one section that was of particular interest to me is the one on data. And how lessons from data failures during SARS weren’t implemented. While focused on health care workers, the data failures extend far beyond that.
Read 11 tweets
7 Oct
And today's covid numbers are up. More evidence that the initial decrease we saw a little over a week ago has given way to a slow increase. Image
Testing is down, usually we see numbers going up at this point in the weekly testing cycle. Hopefully that's just a short term blip. Image
And with testing down, positivity is up. Not a good sign, hopefully we get those test numbers back up. Image
Read 4 tweets
23 Apr
Introducing census tract level T1FF tax filer time data for years 2000 to 2017 at the census tract level as open data. Available for mapping on CensusMapper or API access via web interfaces or {cancensus} R📦. Made possible through a project with CMHC.…
The data is annual, so it's great for timelines. Census tract level enables to see neighbourhood level change. And T1FF data goes beyond just income variables, here is a view into the annual change of 5-11 year olds 2001 through 2017.
Of course the data has lots of income related variables. Here is the change in (inflation-adjusted) median couple family income between 2001 and 2017.
Read 6 tweets
1 Apr
Good to see open data. Should allow programmatic back-filling of data @ishaberry2 and @covid_canada have been collecting manually. Does not yet contain today’s new numbers, hopefully they will improve update frequency.
Would love to see this kind of data from other provinces too. BC used to publish case details in daily briefings, but stopped March 13th. The fine folks at @Data_BC have the expertise and technology to implement an API in a heartbeat, all it takes is political will. cc @adriandix
Added benefit of having clean data like this is that we can immediately pull together descriptive stats. And they are reproducible and can automatically be updated when new data is available.
Read 6 tweets

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