If Omicron is mild, why are so many people dying in Ontario?

While Ontario's rate of new COVID-19 infections appears to have slowed from its record peaks, the daily death toll in this Omicron wave is still on the rise and approaching a level as high as any point in the pandemic.

There are also no signs that the death rate is slowing down. Scientists expect Ontario's daily reports to continue to trend upwards into February, even after the province begins easing COVID-19 restrictions on Monday.

During the third week of January, the most recent week for which full figures are available, Public Health Ontario recorded an average of 52 COVID-19 deaths per day, a rate only exceeded at the peaks of the first and second waves.

The mounting number of deaths raises questions. If Omicron is a milder version of the novel coronavirus, why are so many people dying, and what's going on with the effectiveness of vaccines? 

The answers are found in the sheer numbers of people getting infected by the Omicron variant, says Tara Moriarty, an infectious disease researcher and associate professor at the University of Toronto. 

"We're seeing scales of infection that we have not seen in the entire epidemic to date," Moriarty said in an interview. "There are going to be a lot of deaths, even if the virus is half as severe [as previous variants]."

Public Health Ontario's official count of COVID-19 deaths so far this month has already exceeded 1,000. Given the lag between the day that a death occurs and its entry into the provincial database, this puts January 2022 on track to be one of the three deadliest calendar months of the pandemic. 

The growing death toll shows the impact of the Omicron wave, says Dr. Jerome Leis, medical director of infection prevention and control at Sunnybrook Health Sciences Centre in Toronto.  

The Omicron variant "has likely infected more people in five weeks than all of the rest of the pandemic combined," said Leis in an interview.

"By virtue of so many infections, even a milder severity will translate into a significant number of hospitalizations and deaths, and that's what we're seeing now." 

Among those dying are some people who had been vaccinated against COVID-19. However, that is not proof that the vaccines aren't working.

"Without the high level of vaccination that we have in Ontario, it would have been far worse," said Leis. 

There's substantial evidence from around the world showing reduced rates of death and hospitalization among vaccinated populations. There's also fresh Ontario-based research demonstrating the effectiveness of vaccines against severe health outcomes specifically from the Omicron variant.

The new study, which is yet to be peer-reviewed, found that having three doses of a vaccine is about 95 percent effective in preventing hospitalization or death from the Omicron variant, while two doses are 80 to 85 per cent effective, said Dr. Jeff Kwong, senior scientist with ICES, a research institute focused on health issues in Ontario.