Talks to reduce the waiting time for Covid booster jabs from six to five months are underway amid concerns about the speed of the rollout.
Nine million more people could receive a booster jab if the change happened now doubling the number of those eligible, according to analysis.
Care Minister Gillian Keegan told Sky News: "The JCVI look at all the data. They’ve advised us six months.
“Of course they continually look at the data but they are the only people who can really answer this question.
“If they advise us, our job then would be to get ready to do whatever they say. But at the moment it is six months.”
She added: “It is not unknown, the JCVI have changed over periods of time and have reacted.”
Prime Minister Boris Johnson said the time period between doses was an “extremely important point” and stressed the need to “keep going as fast as possible” to deliver booster jabs.
But there are differing opinions within the JVCI over the proposal, with a leading expert saying the main issue around Covid boosters is encouraging people to take them up, rather than the timeframe between doses.
Professor Anthony Harnden, deputy chairman of the JVCI, said it was looking at cutting the timeframe between second doses and boosters from six months to five.
It comes amid a media blitz launched by the government which is encouraging people to take up booster jabs.
The nationwide advertising campaign is set to run on outdoor billboards, broadcast and community radio and TV to support the national vaccine drive.
An estimated 4.7 million booster doses of Covid-19 vaccine have been delivered in the UK.
The six-month wait had initially been implemented because it was deemed to be the right time to restore waning immunity.