It is understood the Prime Minister met with a group of MPs for 35 minutes on Thursday morning which included Ashfield MP Lee Anderson who has since tested positive for coronavirus.
Johnson, who has already had Covid-19, was subsequently instructed to self-isolate by NHS Test and Trace. He is expected to continue speaking to the country during his self-isolation period.
Anderson confirmed he tested positive in a Facebook post on Sunday night. He, and his wife developed symptoms on Friday and on Saturday, Covid tests confirmed they had contracted the virus.