Asked whether tens of thousands died because of government action or inaction, the prime minister told reporters: “No I don’t think so”.
Johnson also initially refused to say whether Cummings was telling the truth in his explosive evidence on the handling of the pandemic to a committee of MPs on Wednesday.
“I make no comment on that,” the PM said.
But when Cummings’ claim the PM was “unfit for the job” was put to Johnson, he replied: “Some of the commentary I’ve heard doesn’t bear any relation to reality”.
Cummings also claimed it was “nonsense” to say care homes were protected during the pandemic, as people were being admitted from hospital without being tested for Covid.
But Johnson said: “We did everything we could to protect the NHS and to protect care homes as well.
“We put £1.4bn extra into infection control within care homes, we established a care homes action plan, I remember very clearly, to ensure that we tried to stop infection between care homes. We remain very vigilant.”
Central to Cummings evidence were claims that the government had no plan for a coronavirus pandemic, which meant it was slow in locking down in March 2020.
And he personally criticised Johnson for ignoring scientific advice calling for a “circuit breaker” lockdown in September, and instead adopting a “hit and hope” strategy and comparing himself to the mayor in Jaws who kept the beaches open despite a killer shark lurking in the water.
But Johnson insisted: “This has been an incredibly difficult series of decisions, none of which we have taken lightly.
“You’ve got to recognise, and I hope people do understand this, that when you go into a lockdown it’s a very, very painful, a traumatic thing for people’s mental health, for their lives and their livelihoods.
“And of course you’ve get to set that against the horrors of the pandemic and of Covid.
“And at every stage we have been governed by a determination to protect life, to save life, to ensure that our NHS is not overwhelmed, and we followed to the best we can the data and the guidance we’ve had.”