Britain has been advised to avoid offering coronavirus tests to the general public and could now take a different strategy to successful countries such as Germany.
If taken up by ministers it will mean millions of Brits staying off work despite not having Covid-19 during the long-awaited exit strategy.
Mass community testing has until now been seen as the benchmark strategy to aim for as the UK increases lab capacity.
However a key team of infection modellers at Imperial College London claim routinely screening only carers will be just as effective.
It has published findings predicting a scenario where members of the public who report symptoms, possibly on a new app, are assumed to have Covid-19.
These individual’s recent contacts would then be traced and ordered to self isolate as a precaution.
It would see the UK again take its own path in dealing with the outbreak.
Imperial’s MRC Centre for Global Infectious Disease Analysis is Britain’s most influential Covid-19 team advising the Government.
Its estimate of 260,000 deaths was behind Prime Minister Boris Johnson ’s previous U-turn to initiate complete lockdown.
Other countries have decided to ramp up testing to screen the general public for Covid-19, then use these results to trace and isolate those who have come in to contact with anyone who tests positive.
Mass walk-in and drive-through testing has kept death rates extremely low in countries such as Germany, South Korea, Vietnam and Singapore.
In Germany anyone can get a test even with mild symptoms as long as they are referred by a doctor.
The new findings suggests UK testing could be restricted to the seven million key workers if they or their family experience symptoms.
These include NHS staff, care workers, hospital cleaners, supermarket staff and delivery drivers.
Out of these health and care workers could be tested more regularly even if they have no symptoms.
Author Prof Nicholas Grassly, from Imperial, said: “We find testing is most useful when targeted at high risk groups such as healthcare and care home staff.
“Regular screening in addition to testing of symptomatic individuals may prevent an additional 25% to 33% of their contribution to transmission in hospital and the community.”
Weekly testing of NHS staff working in intensive care, infectious disease and respiratory medicine – even if they were not showing symptoms – would require only 5,000 tests a day
The paper concluded: “Widespread PCR testing in the general population is unlikely to limit transmission more than contact-tracing and quarantine based on symptoms alone, but could allow earlier release of contacts from quarantine.
“Testing is essential for pandemic surveillance but its direct contribution to the prevention of transmission is likely to be limited to patients, healthcare workers and other high-risk groups.”
The findings will prompt fears Britain could adopt a different strategy because it has failed to increase its testing capacity.
Health Secretary Matt Hancock admitted the country started from “a low base” when promising 100,000 daily tests by the end of the month. The UK is still testing just over 20,000 a day.
The MRC Centre’s head, Prof Neil Ferguson, previously admitted before MPs that a controversial decision to then abandon community test, track and trace on March 12 was informed by the fact Public Health England had nowhere near enough lab capacity.
The UK was an outlier with its previous “herd immunity” strategy when it delayed lockdown after ministers assumed widespread infections were inevitable.
That was before the MRC Centre published a bombshell paper predicting that without lockdown we would have 260,000 deaths and see the NHS overwhelmed.
Its latest findings come after the Government has finally put testing back at the heart of its virus strategy, after offering tests to symptomatic key workers and their families.
The Government has now started recruiting 18,000 people – including 3,000 clinicians and at least 10,000 call centre staff – to perform contact tracing in future.
A spokesman for Doctors in Unite said: “The government has acted far too slowly to change the fate of over 18,000 people who have already died.
“With each prevarication and each false promise an irreversible choice was made.
“When China, then Italy, then France were locking down, our government should have known what had to be done. But they waited.”