LONDON (Reuters) - British Prime Minister Boris Johnson will plot a path out of COVID-19 lockdown on Monday in an effort to gradually reopen the battered $3 trillion economy, aided by one of the fastest vaccine rollouts in the world. With more than 120,000 fatalities, Britain has suffered the world’s fifth-highest official death toll from the pandemic and its biggest economic crash in more than 300 years. But a fast start to the vaccine rollout plus a near-two month tough national lockdown means Johnson can now set out a phased easing of the restrictions, prioritising a return to schools and social mixing outdoors. “Our decisions will be made on the latest data at every step, and we will be cautious about this approach so that we do not undo the progress we have achieved so far,” he will say, according to his office. Under pressure both from politicians in his own Conservative Party to restart the economy, and from scientific advisers who fear a resurgence of the virus if he unlocks too quickly, Johnson has a difficult course to chart. He has appeared much more cautious in recent months and his health minister Matt Hancock said on Sunday any easing, such as the reopening of schools on March 8, would be followed by a couple of weeks to detect the impact on the wider population. Johnson will set out four tests to be considered before each new relaxation is taken, including the speed and success of the inoculation programme, the state of infection rates and the impact of any new variants of the virus. Britain moved faster than much of the West to secure vaccine supplies and has been inoculating people rapidly since December, a strategy that has driven sterling and stock markets higher on hopes of an economic rebound. Some 17.6 million people, over a quarter of the 67 million population, have now received a first dose, behind only Israel and the United Arab Emirates in vaccines per head of population. The government aims to give a first dose to all adults by the end of July. Hancock also said the country had recently succeeded in driving down cases of the more infectious South African variant. Overall daily coronavirus cases hovered around 11,000 a day last week, compared with a high of over 80,000 in late December. Johnson will set out the roadmap for England on Monday and lawmakers will have the chance to vote on it in parliament. Leaders in Scotland, Wales and Northern Ireland will also ease restrictions over the coming months.