“We’re not going to stop people traveling,” PM Boris Johnson said during a news conference on the Omicron variant. He went on to say PCR tests will be required of anyone who enters the U.K. by day 2 of their arrival. U.K. Prime Minister Boris Johnson announced new measures to combat the spread of the omicron coronavirus variant, which he said can spread rapidly and affect those who are double vaccinated. The announcement of travel restrictions and a tightening of face mask rules for retail stores and on public transport came hours after his government confirmed two cases of the new Covid-19 strain in the U.K, detected in people returning from southern Africa. The U.K. will now require anyone entering the country to take a PCR test within two days of arrival and self isolate until they receive confirmation of a negative result, Johnson said at a press conference. Anyone testing positive, will have to self isolate for 10 days, regardless of their vaccine status, he said. Rules on wearing face masks in businesses and on public transportation will also be tightened. Omicron “might reduce the protection of our vaccines over time,” Johnson said. “So, we need to take targeted and proportionate measures while we find out more.” Johnson and other health officials leaned on the country’s strong vaccination program -- including an expansion of booster shots -- as the main defense against the new variants. The U.K. on Saturday also added four more southern African countries -- Malawi, Mozambique, Zambia and Angola -- to its travel “red list” effective 4 a.m. local time on Sunday, he said. People returning from red-list countries face a mandatory 10-day quarantine at a managed hotel at their own expense. Ten African countries are now on the U.K.’s red list. The HSA is following up on recent arrivals from the countries, it said in a release. Flights from South Africa, Namibia, Lesotho, Botswana, Eswatini and Zimbabwe were suspended from midday on Friday.