Britain will give more than half its surplus vaccines in future to needy countries, Boris Johnson has announced.   The Prime Minister will use his first G7 meeting with US President Joe Biden to pledge the “majority” of spare doses to the international COVAX scheme.  It comes after the UK ordered 407million doses of potential vaccines - enough for every UK adult almost four times over.  The first of any surplus doses, which No10 said would go to COVAX’s procurement pool to support developing countries, are set to be identified later this year.  But there is no deadline - and no firm guarantee there will be surplus doses to give away before Christmas.   in the Autumn. The UK has pledged to give all its adults a first dose by September.  COVAX - led by international bodies including the World Health Organization - is promising “fair and equitable access” to a jab “for every country in the world”, including doses for at least 20% of each nation’s population.  The UK has already paid £548million into the scheme and will encourage other nations to do the same at Friday's G7 mini-summit.  Boris Johnson will host a virtual meeting at 2pm with the leaders of Canada, France, Germany, Italy, Japan and the US - as well as the Presidents of the European Council and the EU Commission.  The UK will urge G7 allies to strengthen work between democratic countries to help recover from the pandemic.  It comes after a spat last month over vaccine supply with the EU.  There is no guarantee yet which countries would receive the UK’s surplus doses or whether wealthier nations might also benefit.  Sources insisted well over 50% of any surplus UK stock was expected to go to the COVAX pool.  But Romilly Greenhill, UK Director of The ONE Campaign, said: “The Government needs to be going much harder and faster.  "Sharing surplus doses through Covax is the right thing to do, but there is a real risk of double standards if we talk a good game on global vaccines access but continue to stockpile more doses than we need.  "The virus won’t wait on us to be ready before it mutates, so we need to get these vaccines around the world as quickly as possible.  "If we want to beat this virus and project people at home and abroad, we cannot rely on a trickle down approach to vaccine access.”  The UK, which holds this year’s G7 Presidency, will also announce an “ambition” to cut the time to develop new jabs to 100 days - down from 314 for the first Covid vaccine.  Mr Johnson has asked Chief Scientific Advisor Sir Patrick Vallance to work with the WHO and other global experts to speed up the process for future strains or diseases.  He will say: “We must not rest on our laurels. As leaders of the G7 we must say today: never again.  “By harnessing our collective ingenuity, we can ensure we have the vaccines, treatments and tests to be battle-ready for future health threats, as we beat Covid-19 and build back better together.”  Friday's meeting - Joe Biden’s first get-together of mult