Reaching herd immunity is “not a possibility” with the current Delta variant, the head of the Oxford Vaccine Group has said.

Giving evidence to MPs on Tuesday, Prof Sir Andrew Pollard said the fact that vaccines did not stop the spread of Covid meant reaching the threshold for overall immunity in the population was “mythical”.

“The problem with this virus is [it is] not measles. If 95% of people were vaccinated against measles, the virus cannot transmit in the population,” he told the all-party parliamentary group (APPG) on coronavirus.

“The Delta variant will still infect people who have been vaccinated. And that does mean that anyone who’s still unvaccinated at some point will meet the virus … and we don’t have anything that will [completely] stop that transmission.”