The Ontario government announced on Sunday that adults aged 80 and over are among the priority groups next in line to get the COVID-19 vaccine as part of the first phase of its rollout plan once supply increases.
"Today we crossed an important threshold in the UK's national vaccination program", Johnson said on Twitter.
The Ontario government reported Sunday that all long-term care residents across the province had been "given an opportunity" for a first dose of COVID-19 vaccine.
Britain says it is on track to have offered an injection by Monday to everyone 70 and over, as well as those who are clinically vulnerable, frontline health and social care workers and older adults in care homes.
The UAE now ranks second in the world - after Israel - in terms of the cumulative Covid-19 vaccination doses administered per 100 people worldwide, according to stats shared by Our World in Data.
And more than half a million people received their first dose of the Covid vaccine yesterday.
The Prime Minister confirmed the milestone and described it as an "extraordinary feat" to have vaccinated millions of the most vulnerable people in the country.
The government earlier this year set a target of immunizing its top four priority groups - covering about 14.6 million people - by February 15.
Government data showed the total receiving first vaccines doses was 15,062,189 and 537,715 second doses had also been administered.
The country will start administering vaccines from Monday to those aged between 65 and 69 and the clinically vulnerable to Covid-19, with nearly 1.2 million already invited to book their jabs, the state-run National Health Service (NHS) said.
"We can't let our guard down", she said.
"Those vaccines have been delivered in our NHS hospitals, in GP surgeries, in high street pharmacies, in cathedrals, churches, mosques and temples, in community centres, in living rooms, in cities, towns and villages across England, Scotland, Wales and Northern Ireland".
The National Health Service (NHS) said about 1 million people had already received invitations.
"15,000,000! wonderful team", Nadim Zahawi tweeted, citing data compiled by the I news website using totals from each of the United Kingdom's four constituent countries.
"The vaccine gives us immunity from Covid, but it must also give us permanent immunity from Covid-related lockdowns and restrictions", they wrote.
"The provincial target of providing a first dose offer of vaccine to residents of all long-term care homes and high-risk retirement homes is arriving at completion".
"And of course, that will eventually enable us to lift numerous restrictions we have endured for so long".