Cheap COVID-19 Test Accurately Detects Antibodies Against SARS-CoV-2 from More than 1,000 Blood Samples at Once

The highly accurate test developed by researchers from Swiss Federal Institute of Technology Lausanne (EPFL; Lausanne, Switzerland), University of Geneva (UNIGE; Geneva, Switzerland) and Hôpitaux Universitaires de Genève (HUG; Geneva, Switzerland) can analyze hundreds of samples at the same time, using minute quantities of reagents and single drops of blood.

Antibody testing can be a powerful tool for tracking the spread of SARS-CoV2 infections and to evaluate COVID-19 vaccine efficacy in clinical trials, when scientists look at the rise in antibodies after volunteers get a jab. However, antibody tests rely on rather expensive reagents and typically require larger quantities of blood taken with a venous blood draw, which can only be performed by trained healthcare personnel. What’s more, some of the tests on the market are too inaccurate to deliver reliable results.

To resolve this issue, the group of scientists from EPFL, UNIGE and HUG repurposed a previously developed diagnostics platform so that it could be used to perform SARS-CoV-2 antibody tests. The platform, which can analyze up to 1024 samples at once, consists of a complex network of tiny tubes carved into a plastic chip that is about the size of a USB stick. To perform the assay, the researchers feed individual blood samples and test reagents through the channels of this ‘microfluidic’ chip. If antibodies against SARS-CoV-2 are present in a blood sample, a molecule generates a signal that can be detected as a fluorescent glow under a microscope.

Then the team tested blood samples from 155 individuals infected with SARS-CoV-2, the assay detected antibodies against the virus in 98% of cases. The assay is also extremely specific: it never detected antibodies against the virus in samples from people who had not been infected with SARS-CoV-2. Because the microfluidic device is very small, the amounts of blood and reagents used are a fraction of those required for standard COVID-19 antibody tests. And running hundreds of assays on a single platform means that a person can perform more assays in less time, with potential cost savings on human labor.

To eliminate the need for collecting blood from people’s veins, the team assessed whether they could use blood samples obtained from a finger prick. The researchers tested three commercially available devices to perform finger-prick blood tests, including glucose test strips used by people with diabetes to measure their sugar blood levels. The microfluidics-based antibody test could be successfully run on blood samples collected with all three methods, even when the blood was left to dry and stored for about one week at room temperature, or when samples were shipped by regular mail from Geneva to Lausanne. The researchers believe that this technology could make it possible for people to buy a blood sampling kit at a pharmacy or a supermarket, collect their own blood with a simple finger prick, and mail it to a central laboratory that analyzes the blood sample and returns the test results via email or a smart-phone app.

“The coolest thing about our approach is that you can do a lot of tests at once with minimal reagents, and you could even have people collect their own blood samples at home,” said study first author Zoe Swank, a former PhD student in the EPFL’s Laboratory of Biological Network Characterization.

“The approach of collecting blood in a decentralized way by a simple finger prick that can be even done at home, and a sophisticated laboratory-based assay with high diagnostic accuracy makes this test very attractive for large-scale epidemiological studies,” added Isabella Eckerle. “It could even be used for remote geographic regions that lack sufficient laboratory capacity, for example to conduct seroprevalence studies in Sub-Saharan Africa.”

Related Links:
Swiss Federal Institute of Technology Lausanne (EPFL)
University of Geneva (UNIGE)
Hôpitaux Universitaires de Genève (HUG)