Which lateral flow tests work best?

New data shows which lateral flow tests perform best

How well lateral flow tests work has been the subject of great debate. This is because the tests can give very different results depending upon how they are used.

New data just published from a team within the Department of Health & Social Care (“DHSC”) shows which of the tests delivers the best results. The data is a huge help in understanding which types of test are best avoided, if you use the tests in your business.

The biggest study so far

Between August and December 2020 the DHSC selected 64 lateral flow tests for detailed testing. The evaluation included standardised laboratory tests and, for those that performed well enough, field testing in the Falcon-C19 research study. The kits were also tested and other settings (COVID testing centres, hospitals, schools and in the armed forces).

Nearly 10,000 tests were carried out in strictly monitored circumstances at PHE Porton Down. The results were reviewed by the UK COVID-19 Lateral Flow Oversight group study. 

Published this week in The Lancet the study is the largest national evaluation undertaken so far of lateral flow tests.

Most kits gave poor results

From the 64 different tests 5 had a kit failure rate above the acceptable threshold for use (more than 10% failure is deemed unacceptable). 17 had a false-positive rate below the specificity threshold (<97%) and 28 kits gave a false-negative rate below the ‘Limit of Detection’ threshold.

That meant that nearly 80% of the tests initially evaluated were discarded from study, because they were not considered reliable or accurate enough. Fourteen tests progressed to the field trials.

Of the 14 tested in the field, 3 failed the next stage (“PHE Stage 3a”) of testing and 4 passed. The remaining 7 tests are still being evaluated.

A handful gave promising results

The 4 lateral flow tests that passed have promising performance characteristics for mass population testing. This is most relevant when infection rates are high, because the tests have well known weaknesses when infection rates are low. Separate DHSC data showed over 62% of results were ‘false positives’ from testing in schools.

The report again highlighted the critical impact of training on the accuracy of the tests. Each kit was tested when being used by a laboratory technician or healthcare worker. The accuracy of the tests reduces when they are used in untrained hands.

The four best tests

Of the 64 different types of tests evaluated the 4 so far that were found to have good performance characteristics (high sensitivity, acceptable specificity and low failure rates) were:

• Zhejiang orient Gene Biotech Co. Coronavirus Ag Rapid Test Cassette (“Orient Gene”)
• Anhui Deepblue Medical Technology COVID-19 (Sars-CoV-2) Antigen Test kit (Colloidal Gold) (“Deepblue”)
• Innova SARS-CoV-2 Antigen Rapid Qualitative Test (“Innova”)
• Abbott Panbio COVID-19 Ag Rapid Test Device (“Abbott”)

Although the tests have known weaknesses and more data about their use in asymptomatic testing settings is needed, it is re-assuring that some more clarity is starting to be found about the relative performance of the different tests.

Our current thinking remains that the weaknesses of using the tests in workplace settings marginally outweighs the benefits when infection rates are low, as they are at the moment. This is because the risk of false positives remains high, even if one of the most accurate tests kits are used.

If you do use the kits in your business, we’d counsel using one of the four types mentioned above.