coronavirus pandemic. It is not yet clear who will be alongside him on the podiums.It comes as evidence from a study showed the Oxford Covid vaccine was highly effective in reducing transmission of the virus.Mr Johnson will hail the 'game changer' study which showed a single dose of the vaccine, developed by Oxford University and AstraZeneca could dramatically slash infection rates of the virus.The study has yet to be peer reviewed, but has been welcomed by Health Secretary Matt Hancock and other scientists.Analysis showed the vaccine offers 76 per cent protection up to three months after the first dose and could reduce transmission of Covid-19 by 67 per cent.The Prime Minister has remained under pressure from backbench Conservative MPs to.