BARRIE, ONT. -- The Simcoe Muskoka District Health Unit reports 36 new COVID-19 cases, plus one new virus-related death Thursday.

To date, 188 Simcoe Muskoka residents have died with the virus, mainly seniors.

There are 20 COVID-positive patients in the hospital, four in the intensive care unit.

Thursday's numbers show 18 cases in Barrie, and six in Bradford, while the remaining are spread out across New Tecumseth, Essa, Oro-Medonte, Muskoka Lakes, Huntsville, Bracebridge, and Adjala-Tosorontio. More than half the residents diagnosed are between 18 and 34.

Public health lists outbreaks in six institutions, including Leacock Care Centre and Tudhope Manor Retirement Residence, both in Orillia.

There is also an active school outbreak at Innisfil Central Public School in Lefroy.

Dr. Michael Lisi, chief of staff at Collingwood Marine and General Hospital, says the concern remains around the UK B.1.1.7 variant, as the number of confirmed cases jumped to 182, eight more than Wednesday.

The health unit reports another 13 cases screened positive for a variant of concern, bringing the total to 276. They will require further testing to confirm.

Lisi says the number of UK variant cases has the potential to "increase exponentially."

"Once it starts doing that, you know, getting it under control, by putting on the brakes is like trying to slow down an 18-wheeler at full speed, you have to put that brake on hard, and you have to do it for a long time," Lisi explains.

The region's medical officer of health said earlier this week that he is considering advising the province to return Simcoe Muskoka to lockdown restrictions because of the jump in the infection rate.

Dr. Charles Gardner said there had been a 30 per cent increase in COVID-19 cases in the past week.

He attributed household clusters of cases and the transmission cycle that follows with some of the growth. "There's been this dynamic of households, often households of unrelated people, who have some social interaction that can lead to transmission... that have jobs that can lead to transmission," Gardner said.

Meanwhile, the health unit revealed its plan to start mass vaccinations Thursday, which includes multiple vaccination clinics, drive-thrus and mobile units.

Public health hopes to have at least 75 per cent, or 372,182 residents, immunized by the end of August.

In Ontario, it's recommended two doses of the vaccine be administered within 42 days of each other, but Lisi says those guidelines could change given the supply shortage.

He also urged the public to continue COVID-19 safety measures, even after receiving the vaccine.

"There are no studies which demonstrate exactly how long the protection lasts with the booster shot," Lisi noted.

"Although the vaccine will reduce your chance of getting a serious illness and death, if you catch COVID, there are no studies yet to show whether it will stop you from transmitting the virus to those around you, at home or work," he added.

The Collingwood physician said while there are still a lot of unanswered questions surrounding the vaccine, he highly recommends everyone roll up their sleeves to be immunized.