Former vaccines minister Nadhim Zahawi has confirmed there are now omicron cases in hospital as he warned it would become the dominant coronavirus variant in the UK.

The latest figures from the UK Health Security Agency show there have been an additional 633 confirmed cases of the omicron variant reported across the UK, bringing the total number of confirmed cases to 1,898.

Zahawi said the UK there was now a race between ramping up the booster programme and the variant, which he said would soon overtake Delta as the dominant force in the UK.

Early data has suggested that while omicron may be more transmissible than previous variants, it could result in less severe illness.

However, Zahawi warned that even if that were the case, the high transmissibility rate of omicron could mean that tens of thousands of people will still end up in hospital.

Zahawi said omicron — which has a doubling time of two to three days — was “so infectious that it will dominate and exponentially grow”.

“Let’s do a mathematic exercise for a second,” he said.

“You get to a million infections by say the end of December – 1% is 10,000 severe infections that could be in hospital.

“Three days later it is two million, three days later it is four million. Three days beyond that it is eight million.

“That is the risk, that even if it is milder, say 50% milder than Delta, then the numbers are huge – it is a small percentage of a very large population.”

The government has activated its Plan B measures to curb the spread of the virus, which includes mandatory mask-wearing in most indoor spaces and on public transport, as well as the use of vaccine passports in some settings.

The government faces a major Tory rebellion when those measures are put to the House of Commons on Tuesday, with a number of Conservative MPs openly coming out against the use of vaccine passports in particular.

However, Zahawi denied that the government was introducing a “vaccine passport” and said people were simply being asked to take a free lateral flow test or to be double-jabbed to attend “high-risk events”.

He said the government’s main focus was the “national endeavour” to ramp up the booster programme.

Late last month prime minister Boris Johnson announced a significant expansion of the booster programme to cover all eligible adults, whom he promised would be offered a booster by the end of the January.

However, the BBC’s Andrew Marr pointed out that only 18 per cent of those aged 40-50 had had their third shot, while only 396,000 doses were being delivered each day — short of the 500,000 target.

When asked whether he was worried that not enough people were coming forward for the booster, Zahawi said: “We saw some queues yesterday at walk-in centres, and I have to say people on the whole have been behaving well.

“This is going to be a national endeavour to boost the nation as quickly as possible so we can control omicron and bring back that equilibrium that we had with the virus, as we continue to protect the economy and of course on that journey towards endemic from pandemic status.”