Achim Wolf, Jack Hulmes, Susan Hopkins

Lateral flow device specificity in phase 4 (post marketing) surveillance

publication date
10 March 2021
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Public Health England (PHE) and Oxford University evaluated the performance of the

Innova LFD device against PCR. In phase 2 and 3a, where the same sample was used for

both PCR and LFD specificity analyses, no false positives were detected. We conducted a

Phase 4, post marketing surveillance study in 7,546 individuals with a negative PCR result

and compared those results with the LFD results from a separate sample. This study

identified 21 (0.28%) discordant test pairs and therefore concluded that the specificity of

the LFD device was 99.72%. However, this analysis assumed a sensitivity for the PCR of

100% (i.e. that on all 21 discordant samples the PCR, and not the LFD, gave the correct

result). Analysis of the Phase 4 data can also be interpreted with lower PCR sensitivity

levels and is consistent with a PCR sensitivity ranging from 94.2% to 100% and an

associated LFD specificity ranging from 100% to 99.72%


These analyses support the policy of not requiring PCR confirmation of positive LFDs

conducted at ATSs under current levels of population prevalence. The data will be kept

under review and further post marketing surveillance analyses conducted at regular


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