Ontario will make all adults who are three months out from their second dose of COVID-19 vaccine eligible for a booster shot by Monday, as it works to get a quickly worsening Omicron-fueled wave of the pandemic under control.

The government says that anyone 18 and up who got their second dose at least 84 days ago will be eligible to book their third dose as of Dec. 20.

It also says that pharmacies can begin administering booster doses to adults 18 and up on a walk-in basis as of Dec. 17, three days before the broader rollout.

Meanwhile, capacity limits in indoor venues that seat more than 1,000 people are being reduced by 50 per cent as of Dec. 18.

The third dose plan represents a significant acceleration on Ontario’s previous schedule, which would have seen booster shots limited to adults 50 and up for the next three weeks, prior to them being offered to all other adults who were six months out from their second dose as of Jan. 4.

But with cases involving the Omicron variant now doubling every two days on average and the head of the science table warning of more than 10,000 daily infections by the end of the month, there was mounting pressure on the Ford government to act.

“Just because this new enemy is on the offense, does not mean we can sit back and play defense. We cannot and we will not. We will meet this new enemy with full force because right now the best defense is a lightning fast offense,” Premier Doug Ford said during a press conference on Wednesday afternoon. “I'm issuing a call to arms hospitals, public health units, doctors, nurses, dentists, paramedics, businesses, union workers, first responders and most importantly you. Everyone has a role to play in the next phase of our provincial COVID response. It's all hands on deck and it starts with booster shots. Nothing matters more than getting these third shots in arms.”

The move to substantially broaden the eligibility for third doses comes amid some research that points to the efficacy of vaccines against infection being significantly reduced in the face of the Omicron variant, which now accounts for an estimated 53 per cent of Ontario’s cases.

In fact, the scientific director of the Ontario Science Advisory Table Dr. Peter Juni told CTV News Toronto on Wednesday that if you are six months out from your second dose your chance of getting infected could be as “high as somebody who was never vaccinated.”

But he said that those who have received a third dose of vaccine should still enjoy relatively strong levels of protection against infection estimated at about 75 per cent. That, he said, underscores the need for a more aggressive rollout of third doses.

“The point is we need to scramble and we need to combine this with public health measures even though everyone will hate it,” he said.

Speaking to CP24 Wednesday night, Juni welcomed the shortening of interval between the second and third doses.

“With just two doses, we don't have much protection left if we're more than three months down the line, perhaps 20 per cent. That's very little,” Juni said.

He also noted that the definition of fully vaccinated should now change to include the third dose. Juni added that the third shot should not be called a booster anymore.

"With Omicron, it's clear two doses will not afford the protection we need at a population level to also slow down this highly transmissible virus. That's the challenge," Juni said.

"So, with Omicron, this has become a three-dose vaccine. If we say a booster, we make it optional. Three-dose means you need to have complete protection."

Ontario will work to increase capacity to administer shots

Ontario had dramatically scaled down its capacity to administer vaccines in recent months as the demand for first and second doses plummeted and many city’s closed some of their mass vaccination clinics.

The province, however, is now working to ramp up capacity once again.

On Tuesday Ontario administered a recent high of 127,000 doses of vaccine and in the news release the government indicated that it hopes to have the capacity to administer 200,000 to 300,000 doses per day by next week.

Government officials also says that Ontario is “engaging with large corporations who have the capabilities to implement workplace and community clinics to support the booster dose rollout for employees, their families and the local community.”

The first such clinic will be held by Bruce Power, in partnership with the Grey Bruce Health Unit, starting next Monday.

Speaking with reporters, Ford aknowledged that additional measures are possible to control the spread of the virus but he said that "we are not going to lock down the system to try to get out of this." 

"I wish I had a crystal ball to tell you where the cases will be in two weeks or three weeks. All I am saying is our best defense is to get a booster shot. Locking ourselves down out of this isn’t the solution. What the solution is is making sure everyone goes out and gets a booster shot in every corner of this province and that's our plan and that's what we're going to get done.”

According to the latest data, approximately 1.3 million Ontarians have already received a third dose, accounting for under 10 per cent of the province’s population.

Chief Medical Officer of Health Dr. Kieran said that there are not currently any plans to change the definition of fully vaccinated for the purpose of accessing some non-essential settings. But he suggested that there could be a review of that down the line. 

“We'll be making decisions as we move forward in following the strategy,” he said.