This is the 'best time' to get your booster shot after being infected with COVID-19

Ontario's top doctor says he believes the "best time immunologically" to get a COVID-19 vaccine booster shot is 30 days after an active infection.

Chief Medical Officer of Health Dr. Kieran Moore said separating an active infection and a booster dose by this time frame will allow antibodies to decline and a complete recovery from the virus.

"That is most likely the best time immunologically to get the booster, and it should absolutely be an mRNA vaccine at that time," Moore said. "And it doesn't matter which one, they are both very effective and interchangeable.

Moore said that unlike the first and second doses of the COVID-19 vaccine – which typically takes about 14 days for the body to build protection – people will be provided with stronger protection much quicker.

"With the booster dose, within five to seven days, you have a significant rise in your antibody production and your memory cells retriggered against COVID … It's a much shorter time frame."

Ontario expanded access to COVID-19 booster shots to anyone 18 and above on Monday to combat the surge of Omicron cases in the province. 

Health officials have said three doses of the COVID-19 vaccine will provide significant protection against severe illness. 

Moore said Tuesday that, to the best of his knowledge, no one has been admitted to intensive care to date with an Omicron infection in Ontario. 

Fifteen people out of the more than 4,500 people diagnosed with Omicron have been admitted to hospital, Moore said. 

He stressed that as COVID-19 case numbers continue to rise, so too will the number of people who require hospitalization. 

Last week, Omicron became the dominant strain of COVID-19 in Ontario, Moore said.