Booster shots for Covid-19 vaccines are not currently needed and the doses should be given to other countries, Oxford vaccine chief Andrew Pollard has said in contrast to the position taken by Britain's health minister, reports Reuters.

Pollard, who heads the Oxford Vaccine Group, said that a decision to boost should be based on scientific studies, and there had not been any evidence yet of an increase in severe disease or deaths among the fully vaccinated.

"There isn't any reason at this moment to panic. We're not seeing a problem with breakthrough severe disease," he said at an online briefing with lawmakers. "If there was any falloff in protection, it is something which will happen gradually, and it will be happening at a point where we can pick it up and be able to respond."

Britain is planning for a Covid-19 vaccine booster programme, and health minister Sajid Javid said he expected the booster programme to begin in early September, pending final advice from officials.