Johnson had a meeting with some MPs in 10 Downing Street on Thursday morning, including Lee Anderson, MP for Ashfield who later developed coronavirus symptoms and tested positive, Sky News reported.
"The PM is well and does not have any symptoms of COVID-19," the statement added, reports Xinhua.
The spokesman said the prime minister "will carry on working from Downing Street, including on leading the government's response to the coronavirus pandemic."
Mr Johnson wrote on Twitter on Sunday night: "Today I was notified by NHS Test and Trace that I must self-isolate as I have been in contact with someone who tested positive for COVID-19, reports BBC.
"I have no symptoms, but am following the rules and will be working from No 10 as I continue to lead the government's pandemic response."
The prime minister recovered from COVID-19, the coronavirus-caused illness, after contracting the virus in late March and spending three days in intensive care in early April.
England is currently under a month-long national lockdown until December 2, the second of its kind since the coronavirus outbreak in Britain, in a bid to quell the resurgence of coronavirus.
Another 24,962 people in Britain have tested positive for COVID-19, bringing the national tally to 1,369,318, according to official figures released Sunday.
The coronavirus-related deaths in Britain rose by 168 to 51,934, the data showed.
To bring life back to normal, countries such as Britain, China, Germany, Russia and the United States are racing against time to develop coronavirus vaccines.
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