UK prime minister Boris Johnson has announced the nation's army could be called in to help maintain public order, should the COVID-19 outbreak reach a worst-case scenario. 

Speaking on Tuesday as the government unveiled its "battle plan" to combat the spread of the virus – which includes home working, possible school closures and canceling large-scale events – Johnson didn't rule out drafting in the army if the police force is beset by staff shortages. 

Johnson said: "The army is, of course, always ready to backfill as and when, but that is under a reasonable worst-case scenario."

The UK has so far had 51 confirmed cases of the virus, and Johnson said it was "highly likely" the country would experience more. 

Planning ahead

The government's 28-page action plan foresees that up to a fifth of the national workforce could be absent from work (either by choice or by infection), schools could close and elderly people would be advised not to attend social gatherings. Other measures include delaying non-urgent health care and discouraging all but non-essential travel.

Businesses, meanwhile, could be given extra time to pay their taxes if they are facing short-term cash flow issues.

The government said its strategy was aimed at delaying the peak of the outbreak until the summer, when the weather is warmer and the health service is under less seasonal pressure. This would also allow more time for the development of vaccines.

Johnson will also launch a major public information campaign later this week, setting out how people can limit the spread of the virus, such as washing their hands regularly for more than 20 seconds at a time.

If the outbreak worsens or is severe and prolonged, the government said it would move from seeking to contain and delay the spread to mitigating its impact.

At the same press conference, Chris Whitty, England's chief medical officer, said it was unlikely Britain would "lock down" any cities to combat the virus.

"Locking down a city is most useful when it is starting in one place with a high transmission in that place and nowhere else," Whitty said.

"It seems unlikely we will be in that situation in the medium- to long-term future, but it is important that all the options are available to people."

The action plan also raises the possibility of emergency registration for retired health professionals, in case of NHS staff shortages caused by coronavirus.

Derry Roberts, 73, spent more than half a century working as a nurse and could be one of thousands to return to the front line in the battle to contain the virus.

"I think I could [come back] yes," she said. "There's got to be a quick and safe process to get us all re-registered now, not in months' time when it's too late, so that if we're wanted, when we're wanted, we're ready to go."

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