UK's Johnson warns of Omicron 'tidal wave', says two doses not enough

An ambulance drives past St Thomas' Hospital as the spread of the coronavirus disease (COVID-19) continues, in London, Britain, December 12, 2021. REUTERS/May James

LONDON (Reuters) -Britain faces a "tidal wave" of the Omicron variant of coronavirus and two vaccine doses will not be enough to contain it, Prime Minister Boris Johnson warned on Sunday, as he accelerated the booster rollout programme.

Speaking hours after government scientists lifted the COVID alert level to 4 on a 5-point scale, Johnson said the booster programme must go faster because scientists did not yet know if Omicron was less severe than other variants.