Using dried blood spot samples (DBS) is an accurate alternative to venous blood in detecting SARS-CoV-2 antibody tests, according to a study from the University of Birmingham in the UK.
Researchers analyzed serum and DBS samples from volunteers at University Hospitals Birmingham Foundation NHS Trust, some of whom had previously tested positive for SARS-CoV-2 by molecular tests, while the status of other volunteers was either negative or unknown. The anonymized matched serum and DBS samples were then processed using a highly sensitive ELISA test, developed by the University’s Clinical Immunology Service in partnership with The Binding Site, which specifically detects antibodies (IgG, IgA and IgM) to the SARS-CoV-2 trimeric spike protein.
Results showed a significant correlation between matched DBS and serum samples and minimal differences in results observed by sample type, with negligible discordance. Relative to serum samples, DBS samples achieved 98% sensitivity and 100% specificity for detecting anti-SARS-CoV-2 S glycoprotein antibodies; 100% of the PCR-positive samples were also antibody-positive in DBS.
“Our results have demonstrated that dry blood spot sampling not only offers a viable alternative for antibodies testing, but one that overcomes the limitations that current methods can present by eliminating the need for skilled phlebotomists,” says Matthew O’Shea, DPhil, of the University’s Institute of Immunology and Immunotherapy. “DBS offers the opportunity for wider population-level testing and improved surveillance in vulnerable groups such as patients with chronic conditions, the immunocompromised and the elderly by removing the need to come into contact with a healthcare
“As well as offering the opportunity for improved population-wide antibody testing in the UK, the simplicity and cost-effectiveness of the dry blood spot method could improve the effectiveness of sampling in low and middle-income countries, among groups where venipuncture is culturally unacceptable or in geographically dispersed populations,” says Adam Cunningham, PhD, from the Institute of Immunology and Immunotherapy.
Morley GL, Taylor S, Jossi S, et al. Sensitive detection of SARS-CoV-2–specific antibodies in dried blood spot samples. Emerg Infect Dis. 2020;26(12). doi: 10.3201/eid2612.203309.
Featured image: An example of a dry blood spot sample card before being processed.