Hamilton rejecting wastewater data for COVID that Ontario health minister calls ‘canary in the coal mine’


Published March 7, 2022 at 8:11 pm

There is something in Hamilton’s wastewater that sets it apart from from the wastewater in all other public health units in Ontario — if the city’s official stance is to be taken at face value.

Hamilton COVID-19 Operations Chief Michelle Baird, speaking for local medical officer of health Dr. Elizabeth Richardson at a virtual media conference on Monday, said that wastewater surveillance data for COVID-19 has not worked “as a predictive measure in Hamilton to date.” Baird took a similar line to Dr. Richardson, who last week stated to media outlets that Hamilton Public Health Services (HPHS) is not using wastewater data because it is too “variable.”

The Ontario Science Table, however, has wastewater on its COVID-19 dashboard. Deputy Premier and Health Minister Christine Elliott, and Ontario Chief Medical Officer of Health Dr. Kieran Moore, have also recently said it has predictive value. Hospitalizations, intensive-care-unit admissions and deaths are known as lagging indicators that illustrate COVID’s toll after the fact.

“There has been some public discussion recently regarding the use of wastewater data to determine the trends as it relates to COVID-19 in our commmunity,” Baird said during prepared remarks on Monday. “Hamilton Public Health Services appreciates the use of wastewater data to determine the trends as it relates to COVID-19. However, it is not something that has worked as a predictive measure in Hamilton to date. We are continuing to work with the researcher to understand the data and its utility locally. Staff are working to obtain further data beyond what we already have.

“We have found the data to be variable as far as using it to determine trends as well as it does in other jurisdictions. To date, Hamilton has found that per-cent positivity and our COVID-19 hospitalization data is more representative of COVID-19’s current prevalence in Hamilton, while other forms of traditional surveillance are less accurate due to testing eligibility changes and the resulting underestimation of cases. Hamilton Public Health Services, however, is continuing to work with the province and researchers to understand how this study is being incorporated into monitoring metrics going forward, and to understand the relationship between wasewater trends and other metrics such as hospitalizations.”

At the end of December, the Ontario PC Party government tightened eligibility to get a PCR (polymerase chain reaction) test, which is more reliable than a rapid antigen test (RAT) for confirming whether you are positive for COVID-19. While COVID-19 case counts are much less of an urgent indicator due to increased vaccination, Moore acknowledged last week that they might be undercounted by a factor of 10.

While PCR test access is limited, everyone uses the bathroom. That is why wastewater samples might give a better illustration of how prevalent COVID-19 is in the poulation. Public health departments for other major municipalities, including Waterloo Region and Ottawa, are using it. However, Hamilton has not made their wastewater data public.

Baird did not provide a direct answer to media questions about why there is a “divide” between Hamilton’s COVID-19 response and the growing scientific consensus.

“We certainly have been looking at this data, and trying to understand its local application,” she said. “We do know that we have some our data that have been more predictive for us in Hamilton. That being said, we are working with the researchers and have some planned meetings coming up in the very near future to understand where (the) divide is and where we could perhaps use this data going forward.”

Elliott: wastewater the ‘canary in the coal mine’

Last Saturday (March 5), the Hamilton Spectator newspaper spoke to University of Ottawa civil engineering professor Robert Delatolla, who said his team has been analyzing waterwater data from Hamilton since mid-2020. Dr. Peter Jüni, who is the scientific director of the Ontario COVID-19 Science Advisory Table, also told the newspaper that wastewater data is reliable.

Further to that, Elliott said Monday it is a tool that the province is embracing. The health minister mentioned wastewater surveillance when asked if the province will drop masking mandates after March Break, which is from March 12-20.

“I know that Dr. Moore is watching that very carefully because … there are certain areas of the province that have higher numbers of COVID,” Elliott told Postmedia during a campaign-style annoucement in Belleville.

“We’re also looking at wastewater surveillance, too, which is sort of the canary in the coal mine that can tell us if there is something that we need to be concerned about that’s coming in the future,” added Elliott, who announced her retirement from elected politics last week but is staying on as health minister under Premier Doug Ford.

The expression Elliott used refers to a practice that coal miners once used to detect dangerous gases such as carbon monoxide in mine tunnels. The miners would carry caged canaries with them; the bird’s death was a signal to evacuate from the mine.

The health minister said during the same media appearance that local public health units can still issue Section 22 orders that call for additional COVID-19 protections. The Health Protection and Promotion Act allows MOHs such as Dr. Richardson is to issue local orders.

‘Risk of transmission will remain high’

Hamilton, by the metrics that public health is using, is in better place with COVID-19 than it was in early January or early February. While hospital networks are under strain, the city is averaging one new hospital admission per day with COVID-19, and fewer than one new ICU admission daily. There has been one new death associated with COVID-19 since March 4, and the positivity rate is 11.2 per cent.

However, an easing of restrictions will keep the risk of transmission high.

“We are cautiously optimistic about the province’s planned easing of public health measures in the weeks ahead, While Hamilton is past the peak of Omicron-driven wave, we anticipate the risk of tranmission will remain high through April as public health measures are lifted. The Omicron surge and the associated number of infections this winter, along with our high vaccination numbers throughout our community, also mean we have a strong line of defence.”

Some 83.6 per cent of the eligible population (age five and up) in Hamilton has had two doses of vaccine against COVID-19. Some 87.3 per cent have had one dose. Third-dose coverage is also up to 52.9 per cent for people aged 12 and over.

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