Detection of coronavirus cases rose by almost a fifth and potentially thousands of new infections were prevented, results of a community testing pilot in Liverpool have suggested.
More than 3,200 staff days among key workers, such as those in the emergency services, were saved from being lost to quarantine through a test-to-release scheme, researchers said.
New cases of the virus dropped by 21% compared with other areas up to mid-December, the study showed, at which point the spread of the Kent variant made it more difficult to compare areas.
The study, by the University of Liverpool and the Department for Health and Social Care (DHSC), ran from November 6, 2020 up to April 30 this year with the aim of improving detection of the virus, using lateral flow testing for people without symptoms.
During this period, more than half – 57% or 283,338 people – in the city took a quick turnaround lateral flow test (LFT) as part of what Liverpool City Council said was a world-first voluntary mass testing programme for people without Covid-19 symptoms.
Some 6,300 individuals declaring no symptoms tested positive by lateral flow – a case positivity of 2.1%, researchers said.
They said the estimated impacts of Liverpool’s community testing compared with other areas were an 18% increase in case detection and a 21% reduction in cases up to mid-December.
Scientists said while a pessimistic model suggests 850 infections were prevented, optimistic modelling suggests 6,600 were prevented.
Professor Iain Buchan, chair of public health and clinical informatics at the faculty of health and life sciences at the University of Liverpool, said they had taken a “cautious approach” with the modelling.
He said: “That’s why we have that wide range between a pessimistic and an optimistic scenario. The reality is it’s probably much nearer the optimistic scenario, if that’s going to be consistent with reducing case rates by a fifth which is what we actually observed.”
While accuracy of LFTs assessed against PCR tests showed that the overall sensitivity of the former was 40%, Professor Calum Semple said the benefit of rapid testing was clear.
The professor of outbreak medicine at the University of Liverpool and member of the Scientific Advisory Group for Emergencies (Sage), said: “We were seeing the benefit of rapid testing in the community on a wide scale and we can see it drove down cases, so arguing the pros and cons of PCR and its sensitivity – you could argue its over-sensitivity – was not what this was about.
“This was about testing one device across our community and seeing how it could get our community back on its feet.”
As part of a test-to-release pilot from early December, Merseyside Police, fire and rescue, and prison service staff were trained in how to take lateral flow tests at home and submit their results, as a way to use daily testing following contact with a positive case to reduce the period of self-isolation.
By March 3 this year, there were 709 key worker participants and 3,263 days of isolation had been saved, researchers said.
Prof Semple said the approach had been “very effective and kept our emergency services on the road”.
The speed at which test results are available using lateral flow devices compared to PCR tests which are analysed in labs, saved around a day in the time it takes to identify someone as likely to pass on the virus, scientists said.
Prof Buchan said: “The lateral flow devices performed as expected from biology, identifying people with bigger loads of virus, more likely to be infectious – and doing so in less than an hour they enabled isolation a day sooner than was possible with PCR tests.”
Professor Sally Sheard, head of the public health, policy and systems department at the University of Liverpool’s institute of population health, said there must be a “learning point” when it comes to barriers faced by those living in more deprived parts of the city.
The study showed that people living in those areas were less likely to take up testing and more likely to test positive.
She said: “A lot of people in the poorer parts of the city were reluctant to engage with the process because of the very genuine fear that they would lose income if they had to self-isolate, if they were found to be positive.”
She said there is a need to ensure isolation payments are prompt and that there is minimum bureaucracy around assessing who is eligible for them.
Liverpool’s director of public health, Matthew Ashton, said the use of lateral flow tests gives the “opportunity to close down outbreaks at a much earlier stage by that large-scale hyperlocal deployment of LFT”.
He added: “We hope our learning can be used by Governments here and abroad, not just in managing Covid-19 but also in future pandemics.”
Prof Semple said he could see scenarios in the future, perhaps with other virus outbreaks, where “having this tool (LFT) in our back pocket is incredibly valuable”.
He said: “I would hope that governments would have the confidence in the directors of public health to use these tools should they wish.”