Police could be reduced to just dealing with very serious crimes and maintaining public order, while the NHS could be closed to all but critical care, as part of the government's coronavirus plans.
Under ministers' action plan to deal with a mass outbreak of COVID-19, the disease caused by coronavirus, it has been revealed emergency services all have measures in place to "fulfil critical functions".
But they would have to reduce services should significant numbers of police officers, NHS staff and other public services be struck down by the virus.
The government also confirmed plans were in place to draft in the army, if necessary, to maintain public order.
Prime Minister Boris Johnson said there were "long-established plans by which the police will, obviously, keep the public safe but they will prioritise those things that they have to do".
He added: "And the army is of course always ready to back-fill as and when, but that is under the reasonable worst-case scenario."
Ministers did not put figures on projected mortality rates for a severe outbreak of COVID-19, but confirmed there could be an increase in deaths arising from the outbreak.
Reports of worst-case scenario plans suggest four out of five people could contract the virus with up to 500,000 deaths.
The government action plan, revealed on Tuesday, warned of a depletion in workforces across the UK.
Officials said they were "uncertain of the impact of the outbreak for business" but confirmed that one in five workers could be absent in the weeks the virus peaks.
The government also said it would consider closing schools, encourage working from home and the reduction of large-scale gatherings to slow the spread of the disease.
Universities and further education colleges could also be closed.
Speaking at a news conference, the chief scientific adviser to the government, Sir Patrick Vallance, said restricting travel once the epidemic was "everywhere" would make "no difference at all".
"At the moment we are certainly not recommending any change to behaviours in relation to that," he said.
"And if it grows in the UK, then of course it doesn't really make more sense to say that you're at more risk somewhere else than you are here."
Mr Johnson also told reporters he continued to shake hands with people, adding: "I was at a hospital the other night where I think there were coronavirus patients and I was shaking hands with everybody, you will be pleased to know, and I continue to shake hands.
"People must make up their own minds but I think the scientific evidence is... our judgement is that washing your hands is the crucial thing."
On parents worried about further school closures, Mr Johnson said: "We don't think that schools should be closing in principle - we think if possible schools should stay open but that schools should follow the advice of Public Health England."
Speaking about the concerned members of the public stockpiling food and supplies, Sir Patrick said there was "no reason" to do so.
"There's no reason to be doing any panic-buying of any sort or going out and keeping large supplies of things," he said.
"Clearly, there will need to be measures in cases of household quarantine for making sure that food is in the right place at the right time, but we imagine that could be a rolling case of household quarantine if that measure becomes necessary."
The comments come despite the government plan warning of the possibility of a second wave of coronavirus.
"It is possible that an outbreak or pandemic of COVID-19 could occur in multiple waves and therefore, depending on what the emerging evidence tells us, it may be necessary to ensure readiness for a future wave of activity," the plan said.
The government's 27-page document outlines its response in four stages.
They include containing the outbreak, delaying its spread, mitigating the impact of the disease once it becomes established, and implementing a research programme aimed at improving diagnostics and treatment for COVID-19.
The government's response is currently in the containment phase, along with research being carried out and planning for the delay and mitigation phase.
Officials are hoping to delay the peak of the outbreak until the spring and summer months when health services are less busy.
Earlier Health Secretary Matt Hancock admitted some of the planned action would be "uncomfortable" but insisted the government was "quite prepared to do that if it's necessary".
However, speaking to Sky News' Kay Burley@Breakfast show, he said ministers had not yet ruled out "succeeding in containing the disease" at its current relatively low level.
Mr Hancock said the government was seeking "as targeted an approach as possible" with the focus on elderly and vulnerable people, who are likely to see the biggest impact from the virus.
The number of confirmed coronavirus cases in the UK currently stands at 51.
Many of the cases involve people who have recently travelled to Italy, which has seen the biggest outbreak in Europe.
The European Commission on Monday said the risk level for those in the European Union and UK was "moderate to high".
There are currently more than 91,000 cases of coronavirus around the world and more than 3,000 deaths.
Virus Outbreak: Global Emergency - Watch a special Sky News programme on coronavirus at 6pm weekdays.