Williams said he will determining next steps for use of the AstraZeneca shot in consultation with Public Health Ontario, Ontario's Science Advisory Table and the federal government.
In an interview with Toronto television station CP24, the prime minister said Ottawa has reduced the number of global flights and is open to working with the province to enact more restrictions.
Based on this data, the government has extended the provincewide Stay-at-Home Order that is set to expire on May 19 until at least June 2, 2021.
He said the province must "stay the course" to stop the raging spread of contagious virus variants by keeping in place public-health measures that are slowly bringing down case counts of COVID-19.
"We're not out of the woods yet", Ford said on Thursday.
"It's looking positive to be able to open schools towards the end of May, if the rate of COVID continues to come down in the community", said Dr.
"In the first and second wave when we were dealing wit the non-variants, the number 1,000 was where we had our predictable hospitalization rates around six per cent and ICU rates accordingly", Williams said.
The government also announced Thursday that it would start administering the Pfizer vaccine to children aged 12 to 17 starting the week of May 31.
Ontario’s COVID-19 vaccine booking portal opens for residents 40+
The impact of the public health measures will be evaluated in the coming weeks. "We still have a ways to get back down". Of those, 461,076 are resolved (92.3 per cent) and 8,374 people have died (32 more than Tuesday).
"The stay-at-home order is what's working to really bring the levels down".
"Now that the supply has changed, we need to change our course and nuance our strategy a bit, and that's circling back and making sure that we [fully] vaccinate our older adults". The impacts of these measures will continue to be evaluated over the coming weeks, with consideration being made to the reopening of outdoor recreational amenities on June 2, subject to current trends continuing. But in order for restrictions to be lifted, the province will need to see a sharp decline in daily COVID-19 cases. As a result, the seven-day average of daily cases fell to 2,731 - its lowest point in about five weeks. The number of people with COVID-19 in the province's intensive care units, a key indicator of the health system's ability to cope with the pandemic, remains high.
"We want to assure everyone that sufficient supply will be available for those who want a second dose of AstraZeneca or who can not take an mRNA vaccine (made by Pfizer BioNTech or Moderna)", he said.
The province has been under pressure to relax restrictions around outdoor recreation.
The restrictions were in an effort to curb a growing third wave of COVID-19 in parts of the province fueled by variants of concern.
Schools will also remain closed to in-person learning, with Ford saying health experts wanting schools to open again, while teacher's unions say schools should remain closed.
Ottawa Public Health reported 115 new cases of COVID-19 in Ottawa on Wednesday, while the weekly incidence rate is now 73.2 cases per 100,000 people.