By SYLVIA HUI
LONDON (AP) — Britain says it will offer all adults a booster dose of vaccine within two months to bolster the nation’s immunity as the new omicron variant of the coronavirus spreads. New measures to combat variant came into force in England on Tuesday, with face coverings again compulsory in shops and on public transport. All travelers returning to the U.K. must also take a PCR test and self-isolate until they receive a negative result. So far 22 cases of the omicron variant have so far been identified across the U.K, and the number is expected to rise. Prime Minister Boris Johnson said the aim is to give everyone 18 and up a third vaccine dose by the end of January.