Covid-19: Government ramps up “Moonshot” mass testing

Benefits versus costs

But some experts remain sceptical about the effectiveness and the ethics of mass testing.

Allyson Pollock, professor of public health at Newcastle University, said there was “insufficient evidence” for rolling out what amounted to an “extraordinary experiment across the whole of England where the purpose is far from clear.”

She added, “Normally, if you were going to do a screening programme like this, you would start by asking the advice of the UK National Screening Committee . . . to understand what the feasibility is and to try to get some handle on the harms, the benefits, and the costs.”

Pollock said, “We do not know, based on current evidence, whether screening the general population for SARS-CoV-2 will increase or decrease disease transmission, hospitalisations, and deaths. Detection and isolation of asymptomatic cases could potentially decrease disease transmission, but false reassurance from missed cases could potentially increase transmission, if people then engage in more risky behaviour.”

Mass screening proposals also risk causing harm through “significant diversion of healthcare resources,” she added.

But Matt Ashton, director of Public Health in Liverpool, said, “In the middle of a pandemic with technology developing rapidly, I think you have to try things. This is not going to be a perfect scientific experiment; it’s not a well designed screening programme at a national level. It’s a pilot to test out new approaches”

Ashton said the pilot’s purpose was to try to identify where the virus was in Liverpool and to cut chains of transmission. It would also provide national learning about how mass testing works, how the test itself works, and where it could be most effective.

Performance of the tests

Liverpool is using the Innova lateral flow tests, which the government has spent £500m on procuring.

However, one concern is that although lateral flow tests are rapid they are not as good as polymerase chain reaction (PCR) testing. An interim evaluation by Public Health England’s Porton Down laboratory and the University of Oxford that compared lateral flow antigen tests with PCR tests found that, overall, the Innova lateral test detected covid-19 in 76.8% of cases.4 But performance varied in different settings. It detected 79.2% (95% confidence interval 72.8% to 84.6%) of cases when done by laboratory scientists, 73% (64.3% to 80.5%) when done by trained healthcare workers, but only 58% (52.3% to 62.6%) when done by self-trained members of the public.

The evaluation also reported a 0.32% false positive rate from lateral flow tests across several studies analysed.

Jon Deeks, professor of biostatistics at Birmingham University, said, “While this is a very low rate, the numbers of false positives can still outnumber the number of cases detected when used in mass screening where very few will have the virus. For example, if 100 000 people are tested in a city where the prevalence of covid is 400 per 100 000, assuming the Innova test has a sensitivity of 58% and specificity of 99.6% (as per the testing centre performance), these figures predict the test will give 630 test positives. However, only 230 of these will have covid; 400 of them will be false positives.”

He added, “The poor detection rate of the test makes it entirely unsuitable for the government’s claim that it will allow the safe ‘test and release’ of people from lockdown and students from university.”

Deeks said the evidence “raises serious concerns that the benefits are likely to be few, with serious risks of harm from the public being misled by the unjustified claims of high performance of this test from the government.”

Ashton said that Liverpool was sending confirmatory PCR testing by post to people who tested positive on the lateral flow test and was carrying out daily quality assurance tests to understand the performance of the Innova test. “We know that no test is perfect. You will get false positives and false negatives. In terms of false negatives, we’re in a national lockdown and our information is quite clear that people aren’t allowed to behave differently as a result of that negative test,” he said.

Mass testing of students

The government has proposed a mass testing programme for students to enable them to return home to their families this Christmas while minimising the risk of spreading the disease. England’s NHS Test and Trace will distribute lateral flow tests, with priority given to areas with higher rates of covid-19.

Some universities such as Oxford and Durham are already trialling their own rapid lateral flow testing arrangements.5

Pollock said she was opposed to universities participating in pilots that lacked study protocols. “Universities are meant to be the heart of academic integrity and good science,” she said. “This is a huge experiment, and universities should not be rolling this out.”

But Jacqui Ramagge, executive dean for science at Durham University, who has been overseeing Durham’s pilot for rapid testing of students and staff (box 3), said there was a “balance to be had” when testing new approaches.

“Our pilot is not a research exercise. It’s a service evaluation which is primarily aimed at identifying the logistical and other impediments to running at scale,” she said.

“Until we have a vaccine, mass testing seems to be the best solution, particularly with certain demographics where there’s a higher prevalence of asymptomatic cases.”

Large contracts out to tender

The government seems determined to press ahead with mass testing and has invited bidders to apply for three tenders, worth £43bn in total, to help deliver rapid testing across the country.6 One of these tenders is for a contract worth £912m to supply lateral flow tests.7

Pollock voiced dismay at these figures. “It is a scandalous use of money and public funds to be awarding these contracts without good evidence that the tests work,” she said.