LONDON (Reuters) - British Prime Minister Boris Johnson has cautioned that more families will lose their loved ones to the coronavirus but has taken a distinctly different approach to tackling the outbreak.

A man wears a protective mask as he walks into Oxford Circus underground station in London, Britain March 13, 2020. REUTERS/Simon Dawson

Below is the scientific and public health argument behind the British approach.

WHERE IS THE UK?

The United Kingdom is about four weeks behind Italy and other European countries. Between 5,000 and 10,000 people are believed by scientists to be infected in the United Kingdom.

British cases of coronavirus rose 35% to 798 over the past 24 hours. A total of 32,771 people have been tested in the country, the health ministry said on Friday.

DELAY AND REDUCE THE PEAK

“What you want to do is protect people in the most infectious period,” said Patrick Vallance, the British government’s chief scientific adviser.

Britain wants to “delay the peak and to push the peak down”, he said, to prevent the National Health Service from being overwhelmed and to push the peak into the summer months when the health service is less burdened.

Scientific and medical experts say they are adopting a “staged” approach, not bringing in more stringent measures until the infection rate increases “significantly”, which may not happen until a “few weeks” from now.

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They say the science of the virus is “broadly agreed” internationally but countries will take different measures to tackle the spread.

TIMING IS CRUCIAL

There is no point isolating the entire population at such an early stage as too few are infected, people get fed up with staying at home and a prolonged period of isolation could result in loneliness, the scientists say.

Currently, the British government is asking people to stay at home and self-isolate for 7 days if they have coronavirus symptoms.

Closing schools is not logical at this point as they would have to stay closed for 13-16 weeks, many children would resist social distancing for so long and parents, including those working in the National Health Service, would be forced out of the workplace.

In essence, more stringent isolation measures will be needed but not yet.

“We do need to do it at the last point it is reasonable so that people maintain their energy and enthusiasm to get through what will be quite difficult things to do,” said Chris Whitty, England’s Chief Medical Officer.

Isolating the entire elderly population so early is not logical, according to the government’s scientific advisers.

“Asking elderly people to stay at home - that is one thing that you really have to time... so that it coincides with the period at which the epidemic is at its peak,” Johnson said. “That is one of the reasons we are not triggering that draconian measure now.”

NO WHIPLASH

Isolating the population would suppress the virus temporarily but it would then release it back into population and the entire health crisis would be repeated.

“If you completely locked down absolutely everything probably for a period of four months or more then you would suppress this virus,” Vallance said. “All of the evidence from pervious epidemics suggests that when you do that and then you release it, it all comes back again.”

PROTECT THE VULNERABLE

The disease has five days of mild viral illness, when sufferers could be very infectious, and then a small proportion of people have a second phase in which they have some sort of immune response which causes the damage. The elderly and sick are the ones in the gravest danger.

HERD IMMUNITY

The British scientists do not believe the virus can be eradicated at this stage and that it will return.

“We think this virus is likely to be one that comes back year on year and becomes like a seasonal virus and communities will become immune to it and that’s going to be an important part of controlling this longer term,” Vallance said. “60% is the sort of figure you need to get herd immunity.”