A serological assay to detect SARS-CoV-2 antibodies in at-home collected finger-prick dried blood spots

Abstract

Accurate surveillance of coronavirus disease 2019 (COVID-19) incidence requires large-scale testing of the population. Current testing methods require in-person collection of biospecimens by a healthcare worker, limiting access of individuals who do not have access to testing facilities while placing both patients and healthcare workers at risk of exposure to infection. We report the development and validation of a at-home finger-prick dried blood spot collection kit and an analysis method. We demonstrated 100% sensitivity and specificity using at-home collected specimens across the US. Such methods may facilitate the conduct of unbiased serosurveys within hard to reach populations and help reduce the sample collection burden of serological testing on both health care systems and individuals alike.

Figure 1

SARS-CoV-2 antibodies levels in self-collected finger-prick dried blood spots. Dried blood spot eluents were tested by the ADAP method for antibodies against the S1 protein of SARS-CoV-2. Signals were coded blue for COVID-19 and red for control donors. The y-axis is the signal output from ADAP, calculated by subtracting the Ct value of the specimen to the blank control (buffer C).

Figure 2

Correlation of signals between self-collected finger-prick dried blood spots and venipuncture plasma samples (R = 0.96). Self-collected mail in dried blood spot specimens from COVID-19 (n = 4) and healthy controls (n = 4) were analyzed in comparison to venipuncture plasma samples from the same individuals.