Accuracy of UK Rapid Test Consortium (UK-RTC) “AbC-19 Rapid Test” for detection of previous SARS-CoV-2 infection in key workers: test accuracy study

SPS commentary:

The UK Rapid Test Consortium’s “AbC-19TM Rapid Test” (AbC-19) detects the presence of IgG antibody against the trimeric SARS-CoV-2 spike protein in a finger prick device resembling a pregnancy test. Editorial notes that despite ongoing concerns, the UK Government has committed to purchasing 1 million AbC-19 devices. It adds these findings add to mounting evidence that SARS-CoV-2 seroprevalence studies are limited in their ability to correctly identify people who have and have not been infected. It expresses concern about the risk of false positives and the potential for considerable societal harm. It highlights that although neutralising antibody responses to SARS-CoV-2 infection may persist for months after infection, they can vary considerably between individuals, and the prevalence of detectable antibodies in populations decreases over time. It calls for further work to clarify the relation between circulating antibody concentrations and immunity to SARS-Cov-2. As antibody tests are increasingly available in community pharmacies, it also calls for a clear message to be communicated to the public that positive results from these assays do not provide evidence of immunity. It concludes that this study identifies notable limitations of the UK government’s antibody test of choice and provides good evidence that its specificity in a “real life” setting is highly unlikely to be 100%. Furthermore, apart from limited surveillance to estimate the proportion of a population that has been infected, it considers widespread use of this assay in any other role could risk considerable harm.