TORONTO -- The Ontario government has updated its recommendation for when some people should receive the second dose of the COVID-19 vaccine after it was announced that there will likely be a shortage.

The new recommendation comes after the federal government announced earlier there will be a "temporary" delay of the Pfizer-BioNTech vaccine shipments due to expansions of the company's European manufacturing facility. It could result in a 50 per cent cut in shipments in January.

Ontario’s Chief Medical Officer of Health Dr. David Williams said in a statement on Saturday morning that long-term care and high-risk retirement home residents – and their essential caregivers – who received the first dose of the Pfizer-BioNtech vaccine will receive their second dose in 21 to 27 days.

Staff who were vaccinated within the homes will also receive their second dose within this time period.

The government said that for all other people who received the Pfizer-BioNtech vaccine they will now receive their second dose between 21 and 42 days. 

People who received the Moderna vaccine will receive their second dose after the scheduled 28 days.

The vaccine adjustments align with the recommendations from the National Advisory Committee on Immunization (NACI), the government said. 

Ontario was expecting to receive more than 160,000 doses of the Pfizer-BioNTech vaccine in the final two weeks of January, a delivery schedule that's now in doubt.

Health Minister Christine Elliott told CTV News Toronto on Friday the province is awaiting further details on the "the exact allocations" and the "timing of those allocations" but said the province is once again reserving vials of the vaccine to ensure second doses are administered.

"We have some in reserve to make sure that we are going to be able to do the second doses in the appropriate period of time. So no one needs to worry about whether they will get their second dose or not,” Elliott said.

As of 8 p.m. on Friday, 189,090 initial doses of the COVID-19 vaccine have been administered in Ontario.

With files from CTV News Toronto's Colin D'Mello