Prof Van-Tam also hit back at doctors who have criticised the decision to extend the gap between the first and second doses of the vaccine to 12 weeks.
The British Medical Association has written to the chief medical officer for England urging a rethink, saying that in the case of the Pfizer-BioNTech vaccine a maximum gap of six weeks had been mandated by the World Heath Organisation (WHO).
Prof Van-Tam said that extending the gap was the quickest way to get a first dose to as many people as possible as quickly as possible.
He said: “But what none of these (who ask reasonable questions) will tell me is: who on the at-risk list should suffer slower access to their first dose so that someone else who’s already had one dose (and therefore most of the protection) can get a second?”
BMA council chairman Dr Chaand Nagpaul said that while he understood the “rationale” behind the decision, no other country is taking the UK’s approach.
“We think the flexibility that the WHO offers of extending to 42 days is being stretched far too much to go from six weeks right through to 12 weeks,” he said.
“Obviously the protection will not vanish after six weeks but what we do not know is what level of protection will be offered. We should not be extrapolating data where we don’t have it.”