Public Health Ontario says period of infectiousness does not appear shorter with Omicron
A new guide developed by Ontario’s public health agency suggests Omicron coronavirus infections are contagious for no less time than those of earlier variants, calling into question the province’s move to reduce self-isolation to five days for vaccinated people.
In a guide about how to best cohort patients in hospital published Jan. 21, Public Health Ontario (PHO) said they do not have any evidence to suggest Omicron is infectious for a shorter period of time.
“Modelling data from (Public Health Ontario/Public Health Ontario Laboratory) suggests that Omicron does not appear to be less infectious compared to other variants and that the period of infectivity is not reduced compared to prior lineages and may be increased in certain instances,” Public Health Ontario staff write in the Jan. 21 guide.
They echo Chief Medical Officer of Canada Dr. Theresa Tam, who said this month that the period of infectiousness for Omicron is “no shorter than the other variants.”
University of Ottawa epidemiologist Dr. Raywat Denonandan said Ontario’s current five-day rule is based on “old, pre-Omicron data.”
He cited a Jan. 2022 study from Japan that found highest concentrations of viral RNA in COVID-19 patients “three to six days after diagnosis or symptom onset.”
“When you return to society, that’s when you’re peak infectiousness is,” Deonandan said of the study’s conclusions when paired with Ontario’s current guidance. “But this is all meaningless if you have testing to get yourself out of isolation.”
He said if an infected person can test negative on two rapid antigen tests 24 hours apart, they are likely not infectious and can exit isolation.
Ontario’s official guidance states fully vaccinated people can exit self-isolation five days after symptom onset or a positive test, provided symptoms have “improved” in the previous 24 hours, with no exit testing required.
It was reduced from 10 days after the U.S. CDC published similar guidance in Dec. 2021, in part to ensure basic essential industries did not shut down due to the number of sick people isolating at one time.
Given the emerging science, Deonandan said 10 days would be a better amount of time for people to self-isolate, especially if they have no access to testing.
“Let’s assume you have no testing, what do you do? You should default to the 10-day position, unless you have an extended timeframe with no symptoms whatsoever.”
But he encouraged the government to use all it has, even unused PCR testing capacity, to help workers clear isolation early if they test negative and get back to work.
Ontario Ministry of Health spokesperson Alexandra Hilkene said the reduction in the self-isolation period was enacted by the U.S., U.K. and many other Canadians jurisdictions, and a 10-day isolation period remains in place for vaccinated workers in high-risk settings.
“Recognizing that there is still risk of transmission, individuals who work or live in high-risk health care settings are recommended to return to work after 10 days from their last exposure or symptom onset, or from their date of diagnosis,” she said, adding they can shorten that period to seven days with a negative test result.
Officials commenting on the PHO document said they would not characterize it as providing an opinion or recommendation on isolation length.
For much of the past month, PHO has run a golden banner at the top of its website saying it is “currently reviewing” new Ontario isolation rules brought in because of Omicron.
It disappeared from view of Public Health Ontario’s main page after CP24 asked about it on Thursday.
When asked, PHO spokesperson Janet Wong said the Jan. 21 document is “based on a literature review and jurisdictional scan and is intended to provide information on infection prevention and control best practices for acute care facilities.”
“Policy decisions regarding the period of time for self-isolation is made by the Ministry of Health, not Public Health Ontario.”
Asked specifically about the banner saying PHO was currently reviewing new isolation guidelines, Wong said that review did not involve a scientific evaluation of the province’s new self-isolation guidelines.
“PHO is undertaking a review of PHO documents and resources to align our information with the updated ministry guidance,” she said. “PHO is not reviewing the ministry guidance.”
CTVNews.ca Top Stories
Most of Canada to receive emergency alert test today
The federal government will test its capacity to issue emergency alerts today, with the exception of Ontario, where the test will take place on May 15.
OPINION What King Charles' schedule being too 'full' to accommodate son suggests about relationship with Prince Harry
Prince Harry, the Duke of Sussex, has made headlines with his recent arrival in the U.K., this time to celebrate all things Invictus. But upon the prince landing in the U.K., we have already had confirmation that King Charles III won't have time to see his youngest son during his brief visit.
Ontario man devastated to learn $150,000 line of credit isn't insured after wife dies
An Ontario man found out that a line of credit he thought was insured actually isn't after his wife of 50 years died.
Boy Scouts of America is rebranding. Here's why they've changed their name
After more than a century, Boy Scouts of America is rebranding as Scouting America, another major shakeup for an organization that once proudly resisted change.
Trial begins for Winnipeg serial killer who claims he was mentally ill
The trial of a man who admits he killed four women in Winnipeg is set to begin Wednesday, and a law professor says lawyers for Jeremy Skibicki have multiple hurdles to clear for a defence of mental illness.
These adults born in the '90s partnered with their parents to buy homes in Ontario
An Ontario woman said it would have been impossible to buy a house without her mother – an anecdote that animates the fact that over 17 per cent of Canadian homeowners born in the ‘90s own their property with their parents, according to a new report.
New Canadian study could be a lifesaver for thousands suffering from CTE
A first-of-its-kind Canadian research study is working towards a major medical breakthrough for a brain disorder, believed to be caused by repeated head injuries, that can only be detected after death.
Rape, terror and death at sea: How a boat carrying Rohingya children, women and men capsized
In March, Indonesian officials and local fishermen rescued 75 people from the overturned hull of a boat off the coast of Indonesia. Until now, little was known about why the boat capsized.
Stormy Daniels describes meeting Trump during occasionally graphic testimony in hush money trial
With Donald Trump sitting just feet away, Stormy Daniels testified Tuesday at the former president's hush money trial about a sexual encounter the porn actor says they had in 2006 that resulted in her being paid to keep silent during the presidential race 10 years later.