UK government must urgently rethink lateral flow test roll out, warn experts

UK government plans to widen the roll out of the Innova lateral flow test without supporting evidence risks serious harm, warn experts in The BMJ today.

More than £1 billion have been spent on purchasing lateral flow tests, but Professor Jon Deeks and colleagues argue that the public is being misled about their accuracy, as well as the risks and implications of false negative results, and they call on the government urgently to change course.

Mass testing may be helpful and necessary in certain circumstances if delivered to high quality, they explain, but the Innova lateral flow test is not fit for this purpose.

For example, in the Liverpool pilot study, 60% of infected symptomless people went undetected, including 33% of those with high viral loads who are at highest risk of infecting others. And among students in Birmingham, only 3% of those who would have tested positive on the 'gold standard' PCR test were detected.

Yet the government continues to claim that the Innova test detects 77%, they write, and has championed the use of negative tests to enable visiting relatives in care homes, returning to work or staying in school, despite known exposure to an infectious case.

The government is also relying on mathematical models rather than real world evaluations of testing. They argue that the models used rely on flawed assumptions about test performance and how results will affect human behavior. "Together they tend to overestimate potential benefits and underestimate potential harms."

No one questions the need for evidence based approaches to covid 19 treatments and vaccines. Why then, in the face of so little evidence of benefit, and so much evidence of poor test performance, is the government pushing the rollout, they ask?

It seems at least plausible that this is because hundreds of millions of Innova testing kits were purchased before it was known how they would perform in people without symptoms and when administered by less than expert hands, they suggest. These tests are now sitting in warehouses around the country.

Given all of the above, they call on the government at least to pause the rollout of rapid asymptomatic testing using the Innova test, including its use in care homes, schools, communities and self-testing by untrained people at home, until clearer messaging on the risks of negative results can be developed.

They also ask for full documentation relating to Innova's approval, and for publication of full reports for all studies and models of the Innova test.

What's more, information materials should be revised to make explicit the extremely poor sensitivity of the Innova test for community and self-use among those without symptoms; and the aims, outcomes and full costings of mass testing of keyworkers, schoolchildren, university students, and care home visitors should be reviewed, they add.

"Finally, since testing makes no difference unless followed by appropriate action, the UK needs a national scheme to enable self-isolation of cases and contacts through support, including financial and accommodation for those in need," they conclude.