The next time the Raptors and Maple Leafs play at Scotiabank Arena, it will be half full as the province is reinstating capacity limits for large sports and entertainment venues in an attempt to curb the spread of COVID-19.

The Ontario government announced Wednesday that capacity for indoor facilities that can hold more than 1,000 people will be capped at 50 per cent starting on Saturday, Dec. 18 at 12:01 a.m.

They include concert venues, theatres, cinemas, racing venues, event and meeting spaces, studio audiences in commercial film and television production, museums, galleries, aquarium, zoos, science centres, landmarks, historic sites, botanical gardens, casinos, bingo halls, other gaming establishments, fairs, rural exhibitions, and festivals.

The restrictions, the province said, are being reinforced "to reduce opportunities for close contact in high-risk indoor settings with large crowds and when masks are not always worn.

"I know this will be tough, but it's an important step in ensuring we slow the spread of Omicron as we urgently accelerate boosters because, as I said earlier, it's all hands on deck," Premier Doug Ford said during a news conference announcing the limits.

"This is a call to arms. And now more than ever, we need everyone to be doing their part."

The reintroduction of capacity limits was one of the measures announced on Wednesday amid rising COVID-19 infections in the province and the ongoing threat posed by the Omicron variant of concern, which the Ontario Science Table now estimates is detected in 53 per cent of cases.

Scotiabank Arena has a capacity of 19,800 for Raptors games and 18,800 for Maple Leafs games. With new capacity limits, nearly 10,000 fans would still be allowed inside in each game.

Dr. Kieran Moore, Ontario's chief medical officer of health, said they want to reduce the number of people inside these large venues because there is a concern that Omicron may be spreading more through aerosols than other variants.

"We're having to change our direction in the face of a new end enemy. And Omicron is much more infectious and there is a potential that it can spread in the air," said Dr. Kieran Moore, Ontario's chief medical officer of health.

"So as the premier said, we don't want to close, but we want to limit or decrease the risk in those venues, but we want to limit or decrease the risk in those venues. And Omicron is a definite game-changer. We have to try to decrease the risk of rapid spread in those environments."

Experts have been calling for capacity limits to be reimposed as a way to stop the spread of the virus.

In an interview with CTV News Toronto on Wednesday, science table director Dr. Peter Jüni seemed to suggest that Ontario can avoid the sort of widespread lockdown it had to put in place in the spring, but he said that that capacity limits will have to be reintroduced for many venues in addition to faster booster rollout.

"The point is we need to scramble (on third doses) and we need to combine this with public health measures even though everybody will hate it," Jüni said. "It is not going back to square one with public health measures, that's really important. We learned what is high risk. But unfortunately for restaurant owners, restaurants are high risk. Unfortunately for people who organize a Christmas party at all, that's high risk."

"It's about capacity limits. In sports arenas, you know, 20,000 people is probably too much. We need less people and all of them masked, so drop food and drinks there," he added.

When asked whether the province is planning to introduce more restrictions, including reinforcing capacity limits for restaurants and bars, Ford said everything is on the table.

"I wish I had a crystal ball to tell you where the cases will be in two weeks or three weeks. All I'm saying, our best defence is 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 gonna get done," Ford said.

The premier pointed out that the situation in large venues and restaurants are different, saying comparing the two is like comparing apples and bananas.

"(They) have strict protocols in these restaurants and they've done an incredible job. They're spacing people out, and they're being masked unless you're eating," Ford said.

The Maple Leaf Sports and Entertainment (MLSE), which owns the Raptors and the Leafs, said they are fully supportive of the changes announced by the province.

In a statement, the organization said it will implement enhanced mask protocol during games, warning those who do not adhere will "risk ejection from the building."

The Raptors will host the Golden State Warriors on Saturday, while the Leafs will be back next week to play the St. Louis Blues.

"Our ticketing team is currently working through the logistics of implementing this change and will provide follow up details to all ticket holders within 24 hours," MLSE said.

Speaking to CP24 Wednesday evening, Nick Eaves, MLSE's chief venues and operations officer, said the organization is making adjustments to accommodate fans affected by the changes.

"We're going to take the next 24 hours to make sure that we get this right," Eaves said.

"We want to be equitable. There's obviously a really wide range and mix of ticket holders, and we want to make sure that we're making decisions that really recognize the scope of people that we have coming to games over the next while."

Meanwhile, Mirvish Productions said affected ticket holders will be contacted by email with ticket options.

It said that the capacity limits will only apply to certain performances for Jesus Christ Superstar and Come From Away. The Barenaked Ladies' holiday concerts at the CAA Theatre are not impacted, Mirvish said.