The Prime Minister was forced to self-isolate after he came in contact with a Tory MP who tested positive for coronavirus.
Mr Johnson’s two-week period of self-isolation came after he met with a small group of MPs for a breakfast meeting in Downing Street on November 12, including Lee Anderson, the MP for Ashfield.
The pair were pictured together, not wearing masks, with some suggesting they were standing less than two metres apart.
Mr Anderson subsequently developed symptoms for Covid-19 and tested positive along with his wife Sinead who has cystic fibrosis.
In a leaked WhatsApp message which MPs Mr Johnson sent to MPs, he said: "It doesn’t matter that I feel fine - better than ever- or that my body is bursting with antibodies from the last time I had it.
“The rules are the rules and they are there to stop the spread of the disease.”
NHS national medical director professor Stephen Powis, and Baroness Dido Harding, who leads the NHS Test and Trace programme also revealed they would be self-isolating after coming into contact with people who had tested positive for Covid-19.
In April the Prime Minister was hospitalised with coronavirus and later revealed doctors prepared to announce his death as he was admitted to intensive care at St Thomas' Hospital in London.
Dominic Raab was left in charge of running much of the government when the prime minister was hospitalised by Covid-19 - but Mr Johnson never formally relinquished control.
In May Mr Johnson told the Sun On Sunday: “It was a tough old moment, I won’t deny it. They had a strategy to deal with a ‘death of Stalin’-type scenario.
“I was not in particularly brilliant shape and I was aware there were contingency plans in place.
“The doctors had all sorts of arrangements for what to do if things went badly wrong.
“They gave me a face mask so I got litres and litres of oxygen and for a long time I had that and the little nose jobbie.”