The UK health secretary revealed booster jabs are set to be extended to 18 to 39-year-olds and the waiting time between doses halved in a bid to tackle the Omicron variant.
Making a statement in the Commons on Monday, Mr Javid also insisted any new measures would not last “a day longer” than necessary.
He said: “The new variant has also been spreading across the world.
"Confirmed cases have been reported in many countries, including Austria, Belgium, the Czech Republic, Denmark, Germany, Italy, the Netherlands and Portugal.
“In this race between the vaccines and the virus, the new variant may have given the virus extra legs.
“Against this backdrop of this new variant, we want to go further and faster. So I asked the JCVI, the government’s independent expert advisers on vaccinations, to urgently review how we could expand the programme and whether we should reduce the gap between second doses and boosters.
“The JCVI published its advice in the last hour. First, it advised that the minimum dose interval for booster jabs should be halved from six months to three months. Second, that the booster programme should be expanded to include all remaining adults aged 18 and above.
“Third, that these boosters should be offered by age in group in a descending order to protect those who are most vulnerable to the virus, so priority will be given to older adults and people over 16 who are at risk.”
Mr Javid said new measures were a “huge step up” for the vaccine programme, almost doubling the number who will be able to get a booster dose.
He said: “If it emerges that this variant is no more dangerous than the Delta variant, then we won’t keep measures in place for a day longer than necessary.
“Our experience of fighting this virus has shown us that it’s best to act decisively and swiftly when we see a potential threat, which is why we’re building our defences and putting these measures in place without delay.”
Shadow health minister Dr Rosena Allin-Khan, deputising for Jon Ashworth after he tested positive for Covid, told MPs the variant was “a wake-up call”.
She explained: “The pandemic is not over. We need to act with speed to bolster our defences to keep the virus at bay and it is also an important reminder that no-one is safe until all of us are safe.
“We support the decision to introduce masks on public transport and in shops, but we believe this should never have been abandoned in the first place. Keeping masks in place would always have been our plan A.
“Will the Secretary of State extend the use of masks to hospitality and other settings or does Covid not spread in pubs?”
It came as a former health secretary claimed the Omicron variant came from a failure of Western countries to donate vaccines to poorer nations.
Jeremy Hunt said: “Does he not agree that the fact that we are facing this danger is also a symptom of the failure of western countries to make sure that vaccines are distributed adequately around the world?”