With almost 128,000 deaths, the United Kingdom has the world's fifth worst official COVID-19 toll.
Reuters has reported how Britain was slow to spot the infections arriving, it was late with a lockdown and it continued to discharge infected elderly hospital patients into care homes.
In a blistering attack on the British state, Dominic Cummings told lawmakers on Wednesday that Johnson in early 2020 thought COVID-19 a "scare story" while many ministers, including the prime minister, were on holiday in February 2020, some skiing.
Cummings cast the administrative system as woefully disorganised, dominated by "groupthink" and run by ministers such as Health Secretary Matt Hancock who, he said, should be sacked for lying to the public and the government.
Such was Johnson's scepticism about COVID-19, he even told officials he was considering getting the government's chief medical advisor to inject him with the coronavirus to reassure the public, Cummings said.
Cummings, the strategist behind the 2016 Brexit campaign and Johnson's landslide election win in 2019, left Downing Street, carrying his personal belongings in a box, in late 2020 after falling out with Johnson.
Johnson rejected the criticism from his former adviser, saying he did not accept Cummings' accusation that government inaction led to unnecessary deaths.
"I don't think anybody could credibly accuse this government of being complacent about the threat that this virus posed, at any point. We have worked flat out to minimise loss of life," Johnson said.
So far, Cummings' accusations have failed to harm Johnson's government, which has seen its popularity rise due to the rapid roll out of COVID-19 vaccines to the public.
The committee of lawmakers hearing Cummings' testimony has little power to sanction ministers, but their report will feed into full public inquiry into Britain's response to COVID-19 due to begin in 2022.
"The truth is that senior ministers, senior officials, senior advisers like me, fell disastrously short of the standards that the public has a right to expect of its government in a crisis like this," Cummings said.
He related meetings in early 2020 when it started to dawn on some officials that Johnson's resistance to a lockdown was a deadly mistake. Cummings said there was no COVID plan and certainly no plan for a lockdown.
Bank of England and finance ministry officials worried early on that the bond markets could turn against Britain because of the huge sums that would need to be borrowed, he said.
Cummings said he was sorry for being too slow to hit the emergency button.
"I failed and I apologise," he said, adding that at one point, he pointed to images of Italy on the television in an attempt to convince Johnson that a lockdown was essential.
Cummings said he had told Johnson on March 14, 2020, that the United Kingdom would have to go into lockdown but that there was no plan for a lockdown and there was a fundamental failure to appreciate how swiftly the virus was spreading.
The government's chief scientific adviser, Patrick Vallance, said in March 2020 that 20,000 deaths would be a good outcome. Soon after, a worst-case scenario prepared by government scientific advisers put the possible death toll at 50,000.
The toll is now close to 127,739.
We'll cross to London for discussion and analysis tonight on The Project, 6.30 pm on 10 and 10 Play.