Read on Twitter
Hmm, not really. Look at this: https://twitter.com/melissagrelo/status/1339772726475706368
This corresponds to a prevalence of 1,583 cases per 100,000 asymptomatic individuals. It is extremely high for an asymptomatic population. There are currently 2,703 active cases in the population under 20 years of age in ON. These were found by testing ~45,000 symptomatic people.
The resulting prevalence is ~6,000 cases / 100k ppl with symptoms tested. Since ~55% of the cases in this age group are symptomatic, and if we assume all symptomatic kids were tested (not true), we can expect to find another 2,200 cases among the untested ON population <20 yrs
These are the 45% that are expected to be asymptomatic. Well, if when we tested 3,600 kids in these schools we found 1,583 cases, that means that there should be only another 630 cases out there among all the other 2.4 M kids that were not tested.
Hence, the ON prevalence among <20yo is around 200 cases per 100,000 people (4,900 cases in 2.4 M). That means they found almost 8 times more cases than expected among the tested school population. 1,583/100k when there should be only 200/100k.
This may also be useful, from the same type of misinterpretation done by the government when the Thorncliffe PS tests were conducted. https://twitter.com/dgbassani/status/1333545755194355715
And finally, @krushowy should have read the piece written by her colleague @bruce_arthur before publishing this. It explains clearly how wrong the interpretation was then. As wrong as it is now. https://www.thestar.com/opinion/star-columnists/2020/11/30/positive-covid-tests-at-thorncliffe-park-school-might-tell-us-something-the-ontario-governments-reaction-might-tell-us-more.html
My numbers are not exact, but a prevalence that is 7-8 fold the one expected is pretty far from âlowerâ.
And the headline is misleading, belongs in the Toronto Sun. The 57 cases were found among the 3,600 tests processed so far: âOntario asymptomatic testing program finds 57 COVID cases so far in more than 4,500 tests to date in Toronto, Peel, York, Ottawaâ
False statements in the article. 1: âIt underscores what doctors have said all along: students arenât getting COVID-19 in schools, they bring it into schools from the community,â said the source. **Test data does not say anything about where students are getting infected**
2: âPut this into perspective â in the highest-risk regions, with the highest rates of positivity, we have not seen asymptomatic spread.â *Test data alone does not tell us anything about symptomatic versus asymptomatic spread. Contact tracing and phylogenetic studies do.
And, an infection prevalence in school population that is almost 8 times higher than expected suggests something quite serious is going on in schools. No wonder we are seeing close to 2.5k cases per day in this province this week.
