More than 300 additional health care workers received the COVID-19 vaccine in Toronto Tuesday and officials say that they expect to use up their available supply of the drug by the end of the week.

The first five vaccinations against the novel coronavirus to occur in Ontario took place at the University Health Network’s Michener Institute on Monday afternoon, just hours after a shipment of 6,000 doses landed in Hamilton.

The province has decided to withhold 3,000 of the initial doses so that anyone being vaccinated now is guaranteed their second dose 21 days later.

Meanwhile, the remaining 3,000 doses have been evenly spilt between the University Health Network and The Ottawa Hospital, where vaccines began being administered on Tuesday morning.

Officials say they they expect the initial allotment of 3,000 doses will be used up the end of the week.

“The University Health Network expects to vaccinate approximately 325 people today and another 325 people tomorrow. The good news is there is light at the end of the tunnel and there is hope for everyone out there,” Premier Doug Ford said during a briefing on Tuesday afternoon. “Our challenge is to get more vaccines and get them distributed across the province and into people’s arms as soon as possible.”

Ontario was initially only scheduled to begin vaccinations today but a decision was made to start the process one day early.

Retired general Rick Hillier, who is leading Ontario’s vaccine task force, said on Tuesday that seeing those first individuals from the Rekai Centre long-term care home receive the vaccine was an “incredible moment” and something to “build on.”

He said that once the first round of vaccinations are completed by the end of this week, the focus will shift to preparing to distribute the next shipment, which could include up to 90,000 more doses. Prime Minister Justin Trudeau has said that shipment could arrive as early as next week.

“We remain committed that we will be able to vaccinate as fast as supplies arrive to us,” Hillier said.

Hillier said that once the next shipment of the vaccine arrives it will start being administered at 17 additional sites, as well as at The Ottawa Hospital and UHN.

Ultimately he said that the sites administering the vaccine should be able to provide shots to 1,000 individuals a day and perhaps “significantly more” than that.

While the expectation remains that Ontario will receive enough doses to vaccinate 1.2 million people by the end of the first quarter of 2021 Hillier said that won’t be enough to even vaccinate everyone that falls in the two groups that have been prioritized to receive it first – healthcare workers and long-term care residents.

“If we total up everybody in those two categories we will have more people – about 1.4 million – than we will have supply of the vaccine,” he said.

The province has previously said that the second phase of its vaccine rollout strategy, which will focus on vaccinating Ontarians not prioritized in the first phase, will begin in April and last for six to eight months.