Immunology experts have criticised the British government's strategy of allowing large numbers of people to become infected with coronavirus to develop "herd immunity" so that the more vulnerable do not contract the disease.
On Friday, Patrick Vallance, the UK's chief scientific adviser, said the aim was to "broaden the peak" of the illness but not suppress it, adding that if many people caught it and became immune then transmission would stop.
He suggested that around 60pc of Britons would need to become infected to develop herd immunity and protect those most at risk.
Yesterday, UK Secretary of State for Health Matt Hancock appeared to backtrack on the idea, stating that "herd immunity" was a "scientific concept" rather than the government's goal or policy.
In a letter to the health secretary, Mr Vallance and Prof Chris Whitty, the UK's chief medical officer, the British Society for Immunology (BSI) warned there could be "severe consequences" of infecting large numbers of people when knowledge of the virus was still so limited.
"We don't yet know if this novel virus will induce long-term immunity in those affected as other related viruses do not," said Arne Akbar, the society president.
"Therefore it would be prudent to prevent infection in the first place."
Mr Hancock said yesterday that ministers would "listen to all the credible scientists" as the government faced heavy criticism for not following other countries in introducing stringent measures to prevent infection.
The government has acted slower than many nations in ordering businesses to close and banning large gatherings to stop the spread of Covid-19.
Dr Doug Brown, the BSI chief executive, said: "We have over 4,000 members and researchers and were really quite surprised and concerned that herd immunity appeared to be the government policy."
Dr Brown said there were a "number of unknowns" regarding the virus and that scientists did not know enough about whether those who catch it would develop long-term immunity.
"The common cold is a coronavirus and after three months there is no longer-term immunity to catching it again. We don't know if that will be the case here. We would like to see more social distancing measures that have been brought in in other European countries, such as limiting movement within communities and banning large-scale events and more home-working.
"We should also make sure we are testing some of the most vulnerable people in the community and get them the care and support they need."
The government is concerned that introducing "draconian" isolation measures too soon will risk fatigue, with people emerging just as the virus is peaking, placing them at greater risk. (© Daily Telegraph, London)
I'm used to thinking the country I live in is a bit of a joke. Since I moved to the UK in 2014, these people have elected two disastrous Tory governments, voted for Brexit, and, last week, were named the most nostalgic for their former empire of any European country.
Your greatest friend in the battle against SARS-CoV2, the virus that causes Covid-19, is your own immune system. Its job is to keep you safe from nasty germs that might infect you and most of the time it does a great job. This is why 80pc of people will fight this virus with minor symptoms.