While the FDA’s attempts to evaluate the accuracy of the Covid-19 antibody tests on sale in the US continues in the background, the UK agency Public Health England has conducted a head-to-head study of four of these assays and determined that the one from Siemens Healthineers is the best. The Healthineers test yielded sensitivity and specificity values of 98.1% and 99.9% respectively, beating tests from Abbott, Roche and Diasorin. Healthineers’ test was the only one to meet the performance target set by the UK regulator, the MHRA, of 98% sensitivity and specificity; the other three met the specificity criterion only. The tests’ sensitivity was evaluated using 536 samples from patients with laboratory-confirmed Covid-19, at least 20 days after the patients started having symptoms. Specificity was tested using 994 pre-pandemic blood samples from healthy adults. None of the assays was able to match the accuracy data the companies had submitted to the FDA, underscoring the importance of the US regulator pursuing its own independent evaluations. The FDA has in the past week authorised two more antibody tests, from Diazyme and Assure Tech, as well as five more viral RNA diagnostics.
|UK accuracy findings for four Covid-19 antibody tests|
|Company||Assay||Sensitivity (%) [95% CI]||Specificity (%) [95% CI]||PPV (%)||NPV (%)|
|Abbott||Architect Sars-CoV-2 IgG||92.7 [90.2, 94.8]||99.9 [99.4, 100]||98.0||99.6|
|Diasorin||Liaison Sars-CoV-2 S1/S2 IgG||95.0 [92.8, 96.7]||98.6 [97.6, 99.2]||78.1||99.7|
|Roche||Elecsys anti-Sars-CoV-2||97.2 [95.4, 98.4]||99.8 [99.3, 100]||96.1||99.6|
|Siemens Healthineers||Atellica COV2T||98.1 [96.6, 99.1]||99.9 [99.4, 100]||98.1||99.9|
|PPV & NPV = positive & negative predictive values. PPV and NPV calculated at 5% prevalence. Source: Public Health England & Evaluate Vantage calculations.|
Note: "Other" includes two antigen tests, two home sampling kits and one IL-6 test.