Toronto Public Health to prioritize contact tracing for COVID-19 variant cases

·4 min read
Toronto's public health unit will take a more aggressive role in contact tracing confirmed COVID-19 variant cases.
Toronto's public health unit will take a more aggressive role in contact tracing confirmed COVID-19 variant cases.

(Evan Mitsui/CBC - image credit)

Toronto Public Health (TPH) says the close contacts of people with confirmed variant cases of COVID-19 will be contacted directly by health unit staff to stop the spread of several highly contagious strains of the virus.

That represents a new element in TPH's strategy, which since October has asked that people who become infected with COVID-19 outside of certain high-risk settings reach out to close contacts themselves to let them know they may have been exposed.

"There's a real focus on variants of concern," said Coun. Joe Cressy, chair of Toronto's Board of Health during an interview on contact tracing on Friday.

"We realize these are highly transmissible. There's a critical importance to determine where variants are."

In the event the close contact of a variant case does not live in the city, TPH will also take steps to reach out to their local public health unit so it can initiate a contact tracing plan of its own.

On top of that, any close contacts who are symptomatic will be immediately classified as probable cases.

Friday's numbers show 68 variant of concern cases in Toronto — an increase of 11 since the previous day.

All but one of those cases are the variant first discovered in the UK, also known as B117, which is estimated to be at least 50 per cent more transmissible than the original virus that causes COVID-19. The other case is the variant first discovered in Brazil.

Importance of 'aggressive' tracing of cases

The resource-heavy approach to tracing variant cases lines up with what Dr. Zain Chagla, an infectious diseases physician and associate professor at McMaster University, was hoping to see.

With variant strains of the virus still expected to dominate eventually, "there is going to be a point where [tracing] is futile," he said.

Dr. Zain Chagla, an infectious disease physician for St. Joseph's Healthcare in Hamilton, says he'd like to see Toronto be 'as aggressive as possible' with tracing variant cases.
Dr. Zain Chagla, an infectious disease physician for St. Joseph's Healthcare in Hamilton, says he'd like to see Toronto be 'as aggressive as possible' with tracing variant cases.

Dr. Zain Chagla, an infectious disease physician for St. Joseph's Healthcare in Hamilton, says he'd like to see Toronto be 'as aggressive as possible' with tracing variant cases.

"But one would hope right now, while the timing is good, you do contact trace them aggressively."

Chagla says having staff place the calls also takes the onus off individuals, who may feel ashamed or unwilling to let their contacts know they may have been exposed to the virus.

"If you leave people to tell people they are COVID positive, I think most people will do the right thing," he said. "But it is very hard to make that phone call."

Some contact tracing halted in October

The update to the health unit's game plan also comes nearly five months after it stopped some forms of contact tracing amid rising case numbers.

"When case counts reach a high level, you make a strategic shift and re-prioritize," said Toronto's Chief Medical Officer Dr. Eileen de Villa in an interview with CBC Toronto.

Instead of calling the close contacts of all infected Torontonians, TPH contact tracing teams have been focusing exclusively on outbreaks in high-risk settings like hospitals, schools and long-term care.

"If the impression is that we are not doing [tracing] at all, that's not the case," de Villa said. "We have continued to use case and contact management as one of many tools in response to the pandemic."

The resources TPH has put into its case and contact management unit have also continued to grow.

"When we first started out in early 2020. our team was 50 people," said de Villa. "By the time we were in March or April it was 400 ... and by the fall we actually had expanded that to about 900."

Toronto's Medical Officer of Health, Dr. Eileen de Villa, says everyone who contracts COVID-19 in Toronto gets a call from public health to discuss isolation options and close contacts.
Toronto's Medical Officer of Health, Dr. Eileen de Villa, says everyone who contracts COVID-19 in Toronto gets a call from public health to discuss isolation options and close contacts.

Toronto's Medical Officer of Health, Dr. Eileen de Villa, says everyone who contracts COVID-19 in Toronto gets a call from public health to discuss isolation options and close contacts.

On top of that, 280 staff members from a provincial pool of about 1,000 case managers and contact tracers hired by the Ministry of Health have been working in the city.

Still, there are signs that the health unit is still having issues with contacting individuals effectively, even as it prepares to take on more detailed contact tracing of variant cases.

According to the city's monitoring dashboard, it was able to contact 65 per cent of people infected with COVID-19 within 24 hours.