In a statement to parliament, Sajid Javid told MPs that 10 patients with confirmed Omicron infection had been hospitalised, with one person now confirmed to have become the first in the UK to die while infected with the new variant.
Doctors' leaders called for COVID-19 restrictions to go further - warning that while the government was calling the rapid spread of Omicron an 'emergency', its response was based 'entirely on the vaccine booster programme [and] is missing the wider measures required to control the spread' of the variant.
BMA chair Dr Chaand Nagpaul urged the government to be honest with the public about the impact that responding to the rapid rise in COVID-19 cases would have on NHS services - and warned that NHS staff must not be 'scapegoated or subject to abuse' for a reduction in access to routine care.
Mr Javid told MPs that 4,713 cases of Omicron have been confirmed in the UK and that UK Health Security Agency estimates now put total daily COVID-19 infections at 200,000.
One in five cases in England are now thought to involve Omicron, a figure that rises to 44% in London - where Omicron is expected to become the dominant variant within 48 hours, the health and social care secretary said. He added: 'Hospitalisations and deaths lag infections by around two weeks. So we can expect those numbers to dramatically increase in the days and weeks that lie ahead.'
The BMA has called for changes including the return of 2m social distancing, limits on large indoor gatherings, increased infection control measures in healthcare settings and a widening of requirements for face coverings.
Mr Javid said more than four in 10 UK adults had now received a booster or third dose of COVID-19 vaccine, with a record 483,361 booster doses delivered in England alone on 11 December.
However, general practice and other NHS organisations delivering vaccinations face a colossal task over the coming two to three weeks as the UK seeks to offer boosters to all eligible UK adults by the end of the year. Anyone who received a second dose more than three months ago is now eligible to receive a booster jab - an estimated three quarters of the adult population.
The health and social care secretary said the government was asking GPs and pharmacists to 'do more' - and that vaccination sites would be 'working seven days a week'.
Mr Javid reiterated earlier comments that GP practices will be asked to focus solely on urgent appointments and vaccinations over the coming weeks to boost the COVID-19 vaccination drive - and that non-urgent appointments and some elective care would be postponed until early next year.
Dr Nagpaul said: 'The government’s response relying entirely on the vaccine booster programme is missing the wider measures required to control the spread of Omicron.
'It’s estimated that one in four people will not be eligible for a booster by the end of December, because they will either currently be unvaccinated, or somewhere in the process of having the first two doses. Most are younger people, who are often the most socially mobile and most likely to inadvertently spread COVID-19.
'That is why we need additional protections over and above the vaccination programme, given the significant numbers that will not be due their booster for months into the next year.'
The BMA chair warned that the NHS was 'severely understaffed' - and that maintaining normal services alongside delivery of the accelerated booster programme was 'potentially impossible'.
'The government must face the reality of that,' he warned. 'General practice in particular is facing significant workforce shortages, meaning GPs and their teams cannot do everything for everyone all at the same time. There are significant backlog pressures within the NHS and large volumes of urgent unmet need that simply cannot be delayed, we are discussing with government and NHS England how we can ensure patients get the care they need now and in the coming months.
'Finally, we are calling on the government to be honest with the public about the impact of this new wave of infection on current healthcare services. This must not result in hardworking doctors being blamed, scapegoated, or subject to abuse for the reduction in access to routine services in hospital and general practice. This is not about introducing lockdown restrictions, but about safeguarding the NHS whilst maintaining a functioning society in a safe and responsible manner in the context of an exceptionally transmissible new variant.'