Self-sampling of capillary blood for SARS-CoV-2 serology

Sci Rep. 2021 Apr 8;11(1):7754. doi: 10.1038/s41598-021-86008-5.

Abstract

Serological testing is emerging as a powerful tool to progress our understanding of COVID-19 exposure, transmission and immune response. Large-scale testing is limited by the need for in-person blood collection by staff trained in venepuncture, and the limited sensitivity of lateral flow tests. Capillary blood self-sampling and postage to laboratories for analysis could provide a reliable alternative. Two-hundred and nine matched venous and capillary blood samples were obtained from thirty nine participants and analysed using a COVID-19 IgG ELISA to detect antibodies against SARS-CoV-2. Thirty eight out of thirty nine participants were able to self-collect an adequate sample of capillary blood (≥ 50 µl). Using plasma from venous blood collected in lithium heparin as the reference standard, matched capillary blood samples, collected in lithium heparin-treated tubes and on filter paper as dried blood spots, achieved a Cohen's kappa coefficient of > 0.88 (near-perfect agreement, 95% CI 0.738-1.000). Storage of capillary blood at room temperature for up to 7 days post sampling did not affect concordance. Our results indicate that capillary blood self-sampling is a reliable and feasible alternative to venepuncture for serological assessment in COVID-19.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Specimen Collection / methods*
  • COVID-19 / blood
  • COVID-19 / diagnosis*
  • COVID-19 Serological Testing / methods*
  • Dried Blood Spot Testing / methods
  • Enzyme-Linked Immunosorbent Assay / methods
  • Female
  • Humans
  • Male
  • Middle Aged
  • SARS-CoV-2 / isolation & purification*
  • Young Adult