Far more Ontarians are catching COVID-19 in community settings than previously known, Star analysis finds
|Toronto Star Yesterday 23 May 2020 at 07:23|
As governments across the province move to loosen restrictions meant to fight the spread of COVID-19, a Star analysis of the best available public data reveals far more Ontarians are catching the virus in the community than has been previously known.
The analysis, based on data from the province’s worst-hit local health units, gives, for the first time, a crucial insight into how Ontario’s epidemic has changed.
In short: New infections from outbreaks in seniors homes and other institutional settings are down sharply since spiking in mid-April.
Meanwhile, the number of new cases caught each day everywhere else remains high — near the highest levels the province has seen since the beginning of the pandemic.
About 70 per cent of new cases are now happening in the broader community outside outbreaks in places such as , the Star has found.
The Star’s analysis is not perfect — it does not offer any insights on most of the province’s smaller communities — but it is the closest we can get to answering a question that has so far been impossible to analyze with publicly available data.
A series of delays, inconsistencies and gaps in Ontario’s COVID-19 data reporting have meant that neither the Star, nor the province could say how many new infections each day are happening in the community versus in institutional settings with anything better than a ballpark estimate.
The Star overcame this by combining relevant records made public by the local health units with any additional data that could be extracted by hand from online dashboards. In total, the seven health units included in the Star’s analysis represent nearly 80 per cent of COVID-19 cases seen in the province so far; the end result is our best answer to the question of how many Ontarians are being infected in the broader community.
Relying, instead, on an overall case number that lumps community cases in with falling outbreak case counts risks leaving the mistaken impression the virus’ spread is being contained, said Todd Coleman, an epidemiologist and assistant professor in the Department of Health Sciences at Wilfrid Laurier University.
“It’s not reassuring to see that there are still a large number of cases in the community, which means that spread is still happening,” he said.
Moving forward, he said, the government should wait to see a steady decline in spread over several weeks before taking further steps to reopen the economy.
“The discrepancies between policy and data are very large at this point.”
Ministry of Health spokesperson Catherine Fraser said, in an email, that the province is conducting surveillance to gain a better understanding of the distribution of COVID-19 cases, including in institutional and congregate-care settings, as well in the community.
The ministry’s analysis also says a majority of cases are occurring in the community, she said.
“The Ministry continues to take measures to protect the health of the public through population-level strategies and through case and contact management,” she said.
Also in an email, Hayley Chazan, a spokesperson for Health Minister Christine Elliott, said: “It’s never been more important for people to continue following the public health measures and advice we’ve laid out, so we don’t undo the tremendous progress we’ve made to contain COVID-19.”
She said these measures include physical distancing, wearing a face-covering when distancing is not possible and practising proper cough etiquette and hand hygiene.
The Star’s analysis is based on data from seven health units that together account for more than 20,000 of the 26,260 confirmed and probable cases reported in the province as of Friday evening: Toronto , Ottawa , Peel , York , Durham and Waterloo Regions , and Simcoe Muskoka .
Those units each publish epidemiological curves, or bar charts, of cases by day, broken down by whether they occurred in an outbreak.
Except for Ottawa, the units all publish this information by the day a case was first reported by the unit. Except for Durham, the units also publish the data by “episode date,” a classification, which, because it is adjusted, where possible, to the date a patient first became sick, can be more useful for analyzing the true course of an epidemic. The Star compiled both of these records into two separate tallies that together offer the most complete survey of outbreaks currently available outside of the province’s central reporting system, the integrated Public Health Information System (iPHIS).
Both methods reveal similar stories of how COVID-19 has hit Ontario; beginning in March, the rate of new infections outside institutional settings can be seen to grow exponentially from fewer than five cases a day to 20, 50, 100 and more before plateauing at above 150 per day on average before that month’s end.
It’s around then that a similar, but more severe, trend in new infections begins to appear in outbreaks at Ontario’s long-term care homes, hospitals, shelters and other institutional settings.
That curve inches up to 50 per day on average by around April 1, then rises sharply to 100, 150, 200 daily and up further to a brief mid-April peak of about 300 new COVID-19 infections each day.
But, the Star’s analysis reveals, the rate of new infections in institutional outbreaks fell almost as quickly as it rose — back to below 100 new cases a day on average by this week.
Meanwhile, the average daily tally of cases in the broader community remains high.
Indeed, as daily case counts have begun to rise again in the province this week after several days of decline following the peak in outbreak cases, the Star analysis suggests most of that increase is occurring outside of the outbreaks that have garnered headlines.
The Star couldn’t perform the same analysis on Ontario’s other 27 local health units, which do not publish equivalent data.
The units may include patients’ outbreak status in case records submitted to the province through the reporting system iPHIS, but the province has not made this data public.
Earlier this month, Dr. David Williams, the province’s chief medical officer of health, told the Star there can be a delay of several days before the results of a local investigation into any one case may enter the system.
The province has never published detailed case-by-case data that separates community cases from those acquired in an outbreak.
Earlier this week, Chazan, the ministry spokesperson, told the Star the province was working to add this information to its daily data release .
In the meantime, what Ontarians do now after emerging from months of lockdown is likely to show up in future case trends, University of Toronto epidemiologist David Fisman said.