Boris Johnson announces tougher entry rules to halt spread of omicron variant

The initiatives, including significant entry-rule changes made in response to the new variant, are a sign of how countries are reintroducing rules that many had thought were left behind.

Earlier in the day, Britain announced that two cases of the new variant, first identified in South Africa, had been detected in the U.K. The cases are linked and connected with travel to southern Africa.

Speaking at an evening news conference at 10 Downing Street, Johnson said that anyone entering the country will be asked to take a PCR test on their second day and that they must self-isolate until they provide a negative coronavirus test. He also said that those who do come into contact with someone testing positive for omicron will have to self-isolate for 10 days, regardless of their vaccine status.

Face coverings on public transport and in shops will now be mandatory in England after they were controversially scrapped in July. They have remained mandatory on public transport and in many indoor spaces in Scotland, Wales and Northern Ireland.

Chris Whitty, England's chief medical officer, who was also at the briefing, said Britain is moving quickly because the risks posed by omicron seemed different from those of the delta variant.

"Delta was primarily driven by the ability to spread really rapidly, but less concern about vaccination escape," he said, referring to fears that current vaccines may be less effective against omicron. The push to move quickly on omicron is driven by "at least strong theoretical reasons for thinking that some degree of vaccine escape is likely," he said.

The new omicron variant may, "at least, in part, reduce the protection of our vaccines over time," the prime minister said. The new rules, which will be reviewed in three weeks, will help to "buy time" for scientists to better understand the variant, he said.

The U.K. also added four new African countries to its travel "red list" on Saturday, meaning that travel is now restricted from a total of 10 African countries: Malawi, Mozambique, Zambia, Angola, Botswana, Eswatini, Lesotho, Namibia, South Africa and Zimbabwe. Travelers from those countries will be denied entry into the U.K., unless they are British or Irish citizens or residents, in which case they will have to quarantine at a government-approved hotel for 10 days.

It was clear that Johnson was placing faith in the current vaccine program as he urged a faster rollout of booster shots. "We don't yet, exactly, know how effective our vaccines will be against omicron, but we have good reasons for believing they will provide at least some measure of protection," he said.

He was asked at the news conference if Britons should consider rearranging their plans for Christmas.

Johnson said he was "confident" that Christmas would be "considerably better than last Christmas." Given the severe restrictions on many Britons last December, that's not a particularly high bar.