It came as 595 new deaths were recorded on Wednesday, taking the UK death toll to 50,365.
The UK is the fifth-worst hit country in the world in terms of Covid-19 deaths, according to data from Johns Hopkins University. Only the USA, Brazil, India and Mexico have recorded more people dying with the virus. It is the first country in Europe to pass 50,000 deaths.
At PMQs on Wednesday Mr Johnson said today: “Number one we have the mass testing, the rapid turnaround testing. We also have fantastic news that we have the realistic prospect of a vaccine. Science has given us two big boxing gloves, as it were, with which to pummel this virus but neither of them is capable of delivering a knock out blow on its own.
“That’s why this country needs to continue to work hard to keep discipline and to observe the measures we’ve put in.”
Labour leader Sir Keir Starmer described the official UK death toll passing 50,000 as a “grim milestone”.
The Prime Minister’s boxing comparison was the second sporting analogy used to describe the battle against Covid-19 on Wednesday.
The professor also used an example of a train journey to explain where the UK is with a vaccine, going to great metaphorical lengths to play down the hope and excitement.
He deployed the football analogy to explain that it was not yet known how the Pfizer vaccine would affect transmission of the virus.
“It’s the Play-Off Final and it’s gone to penalties. We’ve stepped up and scored the first one. It doesn’t mean we’ve won the cup, but it shows the keeper can be beaten. That’s basically where we’re at in the fight against coronavirus”, he said.