Outbreaks skew lower city’s COVID stats

Density of living spaces may play a role in infection rates

At first glance, the distribution of COVID-19 cases across the city seems to tell a familiar story that’s been repeated over and over through The Spectator’s ongoing Code Red project.

The lower part of the former City of Hamilton has much higher rates of COVID-19 cases than the wealthier suburban communities of Ancaster, Flamborough, Dundas and Glanbrook, with the Mountain and Stoney Creek somewhere in between.

But the numbers are deceptive. Nearly a third of the 342 COVID-19 cases recorded in the lower former city have occurred in massive outbreaks at just two care homes — 64 residents infected at the Rosslyn Retirement Residence on King Street East and 47 residents at the Cardinal Retirement Residence on Herkimer Street.

Remove those two outbreaks from the equation and the rate of COVID-19 cases in the lower former city becomes equal to the rate in Stoney Creek and just slightly higher than the Mountain.

The COVID-19 data have been broken down to the level of census tracts, as defined by Statistics Canada, and mapped by the city’s public health department.

There are about 140 census tracts in Hamilton, with populations of about 4,000 each on average.

“Mapping is a piece of the who, what, when and where that we do in epidemiology trying to understand the patterns of disease,” said Dr. Elizabeth Richardson, Hamilton’s medical officer of health. “That helps us to also understand what might be happening behind it.”

It’s important to note the data are mapped by the home address of the infected person, not the place where the virus was likely acquired.

It’s also important to note the rates for individual census tracts can be wildly skewed by the presence of a long-termcare facility that has suffered a large COVID-19 outbreak.

For example, the census tract that includes the Rosslyn home has had 65 COVID-19 cases — 64 at the Rosslyn and just one case among the other 2,000 people living in that census tract.

About 45 per cent of the city’s COVID-19 cases are tied to residents of long-term-care facilities and healthcare workers. There have been about 150 cases involving residents of care homes and 180 cases involving health-care workers.

That leaves about 420 cases spread through the rest of the city’s population.

Evidence suggests increased age is a risk factor for coronavirus infection, but Hamilton’s data doesn’t appear to fall in line.

Dundas is by far the city’s oldest community with a median age of 48.2 years, but the rate of COVID-19 infections in Dundas of 82 per 100,000 people is just slightly higher than Glanbrook and Flamborough, which is the city’s second-oldest community.

There is some slight evidence, however, that suggests the city’s COVID-19 rates may be connected with the density of living spaces.

In rural Flamborough west of Highway 6, the infection rate is 44 per 100,000 people, compared to 96 per 100,000 in Waterdown.

The infection rate in rural Glanbrook is one-third the rate of Binbrook.

And there’s been just one case in rural Ancaster compared with 34 in the builtup part of the community.

A U.S. study of COVID-19 cases showed infection rates were nine times greater in larger urban centres and four times greater in high-density suburbs than in non-metropolitan areas.

“The distancing measures get harder to follow if you have to get in your elevator and go up 22 floors,” said Richardson.

The city has begun collecting social and economic data from newly infected COVID patients.

“In the bigger picture in the United States and in Ontario, we do see a differentiation in terms of people from lower income groups and from racial minority groups being overrepresented in the COVID data,” Richardson said.

Steve Buist is a Hamilton-based investigative reporter at The Spectator. Reach him via email: sbuist@thespec.com