Mirror Online reports. A lack of global supplies will dampen the effort to protect the UK for the first part of 2021, he said.A letter signed by Professor Whitty and the chief medical officers for Scotland, Wales and Northern Ireland, said: "We have to ensure that we maximise the number of eligible people who receive the vaccine."Currently the main barrier to this is vaccine availability, a global issue, and this will remain the case for several months and, importantly, through the critical winter period."Vaccine shortage is a reality that cannot be wished away."So far in England 786,000 people have had their first dose of the Pfizer jab.