He said: “We are a country of around 66.5 million.
“There is always going to be new variants. What about mental health?
“You can’t keep us locked up forever. We have to be released at some point.”
A growing number of scientists have called on the Prime Minister to consider postponing step four of the roadmap.
Professor Gupta from Cambridge University told the Today Programme on BBC Radio 4 earlier in the week that the UK could already be in the grip of a third Covid wave.
Dr Griffin pointed out that cases continued to increase exponentially and hospitalisations were also rising.
He added: “Whilst vaccines have proven highly effective in protecting groups that have received both doses, it is the case that a significant proportion of adults along with children remain susceptible.”
The Prime Minister and his senior ministers have said they are ruling nothing out ahead of June 14, when they will make their final decision.