Those least vulnerable to the effects of coronavirus should be permitted to "resume life as normal", some experts have said in a new joint message.
The declaration, named the Great Barrington declaration, was authored by Sunetra Gupta of Oxford University, Jay Bhattacharya of Stanford University, and Martin Kulldorff of Harvard University, and has garnered over 40,000 signatures from around the world.
It calls for a herd immunity approach to tackling coronavirus, in which the old and vulnerable are shielded from the virus while allowing those less susceptible to resume ordinary life.
The argument for the approach
The declaration suggests that the physical and mental health aspects of restrictive coronavirus policies are of "grave concern." Instead, the declaration recommends an approach to the virus called 'Focused Protection'.
The declaration lists some of the effects of restrictions on short and long-term public health as, "Lower childhood vaccination rates, worsening cardiovascular disease outcomes, fewer cancer screenings and deteriorating mental health - leading to greater excess mortality in years to come, with the working class and younger members of society carrying the heaviest burden."
It adds that "keeping students out of school is a grave injustice," while "keeping these measures in place until a vaccine is available will cause irreparable damage, with the underprivileged disproportionately harmed."
They argue that the harms of Covid-19 to the young are less than some other harms, including flu, and that building herd immunity could reduce the risks for everyone.
"As immunity builds in the population, the risk of infection to all - including the vulnerable - falls," the declaration continues.
"We know that all populations will eventually reach herd immunity - ie the point at which the rate of new infections is stable - and that this can be assisted by (but is not dependent upon) a vaccine. Our goal should therefore be to minimise mortality and social harm until we reach herd immunity.
"The most compassionate approach that balances the risks and benefits of reaching herd immunity, is to allow those who are at minimal risk of death to live their lives normally to build up immunity to the virus through natural infection, while better protecting those who are at highest risk.
"We call this Focused Protection."
It suggests that "those who are not vulnerable should immediately be allowed to resume life as normal, while those who are vulnerable or ill remain at home."
Arguments against the approach
The idea of herd immunity has proved controversial among a number of experts. The Great Barrington declaration comes a few weeks after Sir Simon Stevens, leader of the NHS in England, remarked that asking everyone over 65 to shield would amount to "age-based apartheid."
Others have pointed out that the approach ignores growing evidence of the after-effects of "long Covid", where lasting symptoms have debilitated sufferers for months after contracting the virus.
It is also unknown whether herd immunity would actually work as an approach to stem the tide of infections, as immunity may not last for very long.
Professor Jeremy Rossman, for instance, suggested that antibody responses to coronavirus may "decay rapidly", pointing out that there have also been cases of re-infection.
Sweden is an example of a country where herd immunity has been attempted, but statistics show that the country had high mortality rates among the vulnerable - suggesting the same might occur if the method was tried elsewhere.
Professor James Naismith, director of both the Rosalind Franklin Institute and of the University of Oxford, said, "The main signatories include many accomplished scientists and I read it with interest. I will not be signing it however.
"The declaration risks the same error we have seen with the UK's track trace and isolate scheme - one can promise a scheme that is very easy to describe but is hard to deliver."
He added that the declaration omits some "critical scientific information."