Speaking at Prime Minister's Questions, he said Mr Johnson had rejected the advice of government science advisers, who had suggested a circuit breaker when they met on 21 September.
Sir Keir said a "circuit breaker" would help buy time to "save lives, fix testing, and save the NHS".
On Wednesday, British-ruled Northern Ireland, which is outside the tier system, announced the toughest United Kingdom coronavirus measures since the pre-summer peak, shutting restaurants and suspending schools.
MPs erupted into laughter as Sir Keir continued: "Having read and considered the SAGE advice, I have genuinely concluded that the circuit break is in the national interest".
David Greenhalgh said it was "absolutely untrue" that he backed the proposal for a short nationwide lockdown - which Labour is calling for - and demanded an apology from the opposition leader.
"I do not believe that the prime minister wants to set off on a national lockdown, but as ever he is advised by scientists - he takes that decision", Coffey told Sky.
Meanwhile Sir Keir Starmer used a televised press conference to warn that Mr Johnson was "no longer following the scientific advice" by proposing "far less stringent restrictions" than suggested by Sage. "So please let us not lockdown further, it is not working", she said.
Since the beginning of the pandemic, Northern Ireland has recorded 1,156 cases of COVID-19 per 100,000 people, compared with 995 in Wales, 960 in England and 755 in Scotland.
Mr Greenhalgh was among Greater Manchester leaders to sign a statement on the new coronavirus three-tier system, which included a line saying "a number of leaders" in the region supported a national circuit-break. But on top of the "baseline" measures for the most restrictive Tier 3, some additional measures, such as shutting venues including betting shops and casinos, are listed.
Prof Medley said: "People have said this is kicking the can down the road, and it is - you're not saving lives". According to a model revealed by the conservative daily The Timesyesterday morning a "Two-week general re-containment", with instructions to stay at home and closure of schools, would allow, from October 24, the date of the mid-autumn holidays in Great Britain, to "Reduce the number of expected deaths", by the end of the year, "From 19,900 to 12,100" and to limit hospital admissions by half due to Covid-19: the planned hospitalizations would drop, in this hypothesis, from 132,400 to 66,500. Cities and towns with medium, high or very high alert ratings must implement restrictive measures accordingly.
But the PM said the three-tier system was an "opportunity to keep things going, to keep our kids in schools, to keep our businesses going".