Here comes the first Covid-19 fingerstick antibody test

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Several point-of-care tests for Covid-19 have been authorised by the US FDA, but all have been viral RNA or antigen tests intended to diagnose active infection. Yesterday, however, the FDA permitted the first antibody test in this setting. Made by Hangzhou, China-based Assure Tech, the test was already authorised for use in certain labs with venous whole blood, serum and plasma but may now be used at the point of care with a tiny fingerstick blood sample. It can return results in 15 minutes, according to its instructions for use – much faster than the other FDA-authorised antibody tests, which require venous blood samples to be sent to central labs for analysis. In independent tests sponsored by the National Cancer Institute, Assure’s device had sensitivity of 100% and specificity of 98.8% when used with plasma or serum samples. When the test was used with fingerstick whole blood the results were even better, according to data provided by Assure. Tested on fingerstick samples, the assay yielded 100% positive and negative percent agreement – analogous to sensitivity and specificity respectively. Rapid tests like this will be vital to speeding up Covid-19 testing, which is still facing huge lags in the US and elsewhere.

Assure point-of-care antibody test accuracy data
Data source Sample type Measure No of samples Result
NCI Plasma/serum  Sensitivity 30 100%
NCI Plasma/serum  Specificity  80 98.8%
NCI Plasma/serum     PPV for prevalence = 5%   80.8%
NCI Plasma/serum     NPV for prevalence = 5%   100%
Assure Tech Fingerstick whole blood Positive percent agreement* 28 100%
Assure Tech Fingerstick whole blood Negative percent agreement 113 100%
*When used at least 15 days after symptom onset. All data for the two antibodies combined. Source: Assure Covid-19 IgG/IgM rapid test device instructions for use.

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