Rate of COVID-19 three times higher in Ontario's non-white neighbourhoods: Public Health Ontario

Residents of Ontario's most diverse neighbourhoods have been three times more likely to get COVID-19 than those in predominantly white areas — and when they do, have been more likely to suffer severe outcomes and die, according to a sobering report from Public Health Ontario.

"There have been data — predominantly surveillance data — coming out of the U.K. and the U.S. that show that diverse populations were having an increased burden of COVID and we wanted to look at that in Ontario," said Dr. Shelley Deeks, chief health protection officer at Public Health Ontario.

The report comes as public health experts have criticized the province for failing to collect race-based information about individual COVID-19 cases. Local public health units are allowed to collect that information and while the province's chief medical officer of health said over a month ago a province-wide plan was in the works, it has yet to materialize.

The new Public Health Ontario report is based on the neighbourhood each person who tested positive for COVID-19 lives in, rather than each person's individual identity, so it does not determine the rates of COVID-19 among people of different races or ethnicities.

The provincial public health agency analyzed data for COVID-19 cases confirmed positive by mid-May in Ontario, assigning each person to the census dissemination area they live in — a neighbourhood consisting of 400 to 700 total residents. Every neighbourhood was ranked based on its “ethnic concentration" as measured by the Ontario Marginalization Index, which takes into account the number of non-white and non-Indigenous residents and the proportion of immigrants that arrived in Canada within the past five years. The neighbourhoods were divided into quintiles and those with the highest score on the index labelled the most "diverse."

The majority of most-diverse areas are located in the suburban Greater Toronto Area.

After adjusting for differences in the age, and excluding cases in long-term care homes, the rate of COVID-19 infections in the most diverse quintile of neighbourhoods was three times higher than the rate in the least diverse quintile, the report found.

The data also show higher rates of hospitalization, ICU admission among cases in the more diverse neighbourhoods. Rates of death were twice as high among cases in the most diverse neighbourhoods, compared to the least.

Deeks said the report is a starting point and doesn't provide an explanation of why the COVID inequity exists.

"Having said that, it's absolutely not surprising that we found this and we can hypothesize why that is," she said. "With most diseases, it's recognized that social determinants of health play a role in infection."

"We need to do further research into some of these issues and really understand what's happening at the individual level — what we know from other diseases is that often this is a proxy for other factors and the relationships are quite complex," she said, adding that factors at play could include higher risks of exposure to the coronavirus and the prevalence of underlying medical conditions that affect the severity of outcomes, linked to social conditions, as well as access to health care.

The report also examines how the cases in each quintile were exposed, according to the contact tracing work by each public health unit. It found that the distribution of travel-related cases was roughly equal between each quintile, even though the most diverse quintile made up 44 per cent of overall cases and the least diverse quintile made up only 9 per cent of the overall cases.

Strikingly, the cases from the most diverse neighbourhoods were significantly overrepresented among those for whom no information was available. Deeks could not say why that is, except that it suggested the public health units were having trouble reaching those cases.

Some public health units were overwhelmed by the number of new daily cases coming in at the time of the data used in the report, particularly those in the GTA, where the most diverse neighbourhoods are located.

Meanwhile, Deeks said public health Ontario will continue to release more deep dives into COVID-19 data. It has access to more information — such as detailed geographical information — than has been released publicly, something some outside public health experts have been calling for.

On Thursday, PHO released its first weekly epidemiological summary, which included the findings of the diversity report. It also included the topline findings of a report on poverty.

Those findings are based on the same methodology as the diversity report but use the "material deprivation" dimension of the Ontario Marginalization Index, measuring poverty. It found rates of COVID-19 were three times higher in the poorest — or "most deprived" — neighbourhoods than the least deprived neighbourhoods. The full report on that data is coming soon, said Deeks.