Omicron contagion period “does not appear shorter”, says Public Health Ontario


A revelation by Ontario’s public health agency that Omicron’s infectious period may not be shorter than those of earlier variants, has resulted in calls for a reversal of the province’s move to reduce self-isolation to five days for fully vaccinated people.

In a technical brief on cohorting patients in acute care settings published a week ago, Public Health Ontario (PHO) said the period of infectivity with Omicron is not shorter than with other variants and may be increased in certain instances.

“Modelling data from PHO/PHOL (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,” the January 21 guide stated.

On December 30, Ontario shortened the isolation period for fully vaccinated people to five days after the onset of symptoms or a positive test, provided symptoms have “improved” in the previous 24 hours.

It was reduced after the US CDC published similar guidance earlier in December, in part to ensure basic essential industries did not shut down due to the number of sick people isolating at one time.

Around the same time that the PHO guide was released, Ontario Green Party leader Mike Schreiner called on the Ford government to reinstitute the 10-day COVID-19 isolation period and provide the same number of paid sick days to protect essential workers and reduce community spread.

“Ontario should return to a 10 day COVID-19 isolation period to protect frontline workers,” Schreiner said in a media statement. “Reducing it was a premature move by Ford.”

Schreiner referred to experts and recent studies which show that the Omicron variant can be infectious for 10 days like other variants of COVID-19 to back his request.

“Leading experts like Dr. Colin Furness, an epidemiologist at the University of Toronto, are clear that a 5 day isolation period will increase the risk of outbreak at workplaces, which would only make staffing shortages worse,” he stated at the time.


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