LONDON, Dec 12 (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. "A tidal wave of Omicron is coming," Johnson said in a televised statement on Sunday evening. "And I"m afraid it is now clear that two doses of vaccine are simply not enough to give the level of protection we all need." Johnson added that with Omicron known to be much more transmissible than other variants, the National Health Service would struggle to cope with hospitalisations if the variant were to tear through an un-boosted population. "Everyone eligible aged 18 and over in England will have the chance to get their booster before the New Year," Johnson said. Data released on Friday showed that vaccine efficacy against symptomatic infection was substantially reduced against Omicron with just two doses, but a third dose boosted protection up to over 70%. read more In order to hit the accelerated rollout target, military planning teams will be brought in and new vaccine sites opened. PLAN B Johnson has responded to the emergence of Omicron by introducing a "Plan B" in England, ordering people to work from home, wear masks in public places and use vaccine passes to slow the rate of infections. However many of Johnson"s own Conservative Party lawmakers are set to vote against these measures in parliament on Tuesday, and Johnson said there were no plans for further restrictions as cases soar. The seven-day average of COVID cases by date reported has risen in recent days above 50,000 - the highest since the January peak during the last wave of the pandemic. With 146,439 fatalities recorded within 28 days of a positive COVID-19 test as of Sunday, Britain has Europe"s highest death toll from the virus. While that damaged the government"s reputation in the depths of the pandemic, officials have been praised for rolling out one of the fastest vaccine programmes, which helped to contain daily death figures. In recent weeks however questions have once again emerged over Johnson"s future after a series of scandals, the most damaging being reports that parties were held at Downing Street during a 2020 Christmas lockdown when such festivities were banned. A Survation poll for the Daily Mirror newspaper published on Sunday found that 77% of Britons said they were less likely to follow COVID rules if government officials had broken them.