Govt vows to offer Covid-19 vaccine to all adults in UK by autumn
"We're making significant progress, but there's still further expansion to go."
The vaccination drive is ramping up as a coronavirus variant has pushed infections and deaths to unprecedented levels.
'No clear strategy'
Britain on Saturday passed the grim milestone of three million cases during the pandemic, after the government announced another 59,937 new cases.
It also recorded another 1,035 fatalities from the virus, taking the total death toll to 80,868, one of the highest in Europe alongside Italy.
Prime Minister Boris Johnson imposed a third national lockdown for England at the start of the week, with similar levels of restrictions in place in Scotland, Wales and Northern Ireland.
Medical chiefs across the UK are racing to boost treatment capacity as hospitals risked being overwhelmed, while the government has launched a fresh publicity drive urging people to stay at home.
"Of course we are all tired of restrictions, but we must find the collective strength to get through this critical stage and save as many lives as we can," England's Chief Medical Officer Chris Whitty wrote in the Sunday Times.
However, some public health experts continue to criticise the government's pandemic response.
"The UK has no clear strategy beyond reactive lockdowns whenever hospitals are under pressure," Devi Sridhar, head of global public health at Edinburgh University, told Times Radio.
She urged ministers to learn from other countries, namely those in east Asia and the Pacific, which are "largely back to normal".
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Sridhar also cautioned against an over-reliance on vaccines alone to end the restrictions.
"It's not a strategy in and of itself and relying on it alone is highly, highly risky, especially with all the new variants and mutations.
"We need to have a plan and the vaccine supports that plan."
Agencies contributed to this report.