BARRIE, ONT. -- Simcoe Muskoka's medical officer of health is "very seriously considering" advising the province to move the region back to the Grey or lockdown zone.

Dr. Charles Gardner said Tuesday he is concerned about the 30 per cent jump in COVID-19 cases over the past week and the doubling of cases in the City of Barrie.

"This is the first increase that we've seen in Barrie residents over the last three weeks. It's mainly due to non-outbreak-related transmission."

He went on to attribute the growth with household clusters of cases.

"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," he said. "All the household members are affected, and then the cycle continues of transmission."

According to the region's top doctor, Simcoe Muskoka's weekly incidence rate has come the closest to that of the province for the first time since last summer.

"Typically, we've been at half the rate of the province's," he remarked.

Gardner stated the increased case numbers and variant, UK B.1.1.7 cases, as the most troubling.

The region has had 171 confirmed UK B.1.1.7 variant infections, with more than 200 possible variant cases that require further testing to confirm, though Gardner said he believes they will be identified as the UK variant.

"I've communicated to the province my concern about where we're headed and [my] position that we need to be prepared to go into a shutdown again in the near future," he mentioned.

"Our trajectory overall is not headed in the right direction. Our weekly incidents is up from where it was a week ago. It's 46.3 cases per 100,000 population - up from 35.3. By the province's framework, on this indicator, 40 would put us in the red," Gardner said. "We're headed in the wrong direction once again."

The province lifted the lockdown, returning Simcoe Muskoka to the red zone on Feb. 16. At that time, Gardner said he would have preferred the lockdown remain in place since it helped reduce the infection rate following the spike after the Christmas holidays.

He said the province should prepare to reissue the stay-at-home order to avoid a possible third wave.

The ultimate decision to move the region into lockdown lies with the provincial government. However, Ontario's chief medical officer implemented an "emergency brake" that would allow the province to immediately impose a lockdown if it's deemed necessary.

Gardner gave no timeline as to if or when he might pump the brakes, only saying he is watching the situation closely.