Ultra-Specific, Non-Invasive Saliva Test Enables Quantitative Testing Of COVID-19 Antibodies

A home-collection assay for the quantitative testing of COVID-19 antibodies using saliva now makes it possible for individuals to monitor the level of their COVID-19 antibodies over time without leaving home.

Liquid Diagnostics (San Clemente, CA, USA) has developed and successfully carried out CLIA validation of the test which utilizes the company’s proprietary Amperial technology and measures IgG to the S1 domain of the SARS-CoV-2 spike protein. The Amperial chemistry is based on immobilizing biomolecules in a conducting gel matrix and measuring current following electrochemical detection.


This quantitative COVID-19 antibody test is the first home-collection, ultra-specific, non-invasive saliva test. The test is perfect for monitoring both epidemiologic and vaccine response studies because of its unparalleled specificity of this assay and because individuals can collect samples with an easy-to-use mouth swab at home and mail the sample to a centralized laboratory. Results can be returned the day following the receipt of the sample. Individuals can be tested multiple times to assess the persistence of COVID-19 antibody production following exposure or vaccination.

A CLIA evaluation showed that the test has a specificity (absence of false negatives) of at least 99.994% and a positive predictive value of > 96% (the percentage of positive tests that are true positives). The test is classified as a Laboratory Developed Test. An emergency use authorization (EUA) application has been filed and is awaiting FDA clearance.

"With increasing evidence that the presence of SARS-CoV-2 antibodies correlates with immunity to infection, our Amperial assay with its exquisite specificity and high positive predictive value could be useful for essential workers to determine if they have already had a COVID-19 infection and developed immunity," said Dr. Charles Strom, CEO of Liquid Diagnostics, LLC. "Because it quantifies the amount of antibodies, the test could be used to track the persistence of antibodies following infection or vaccination to assess the potential need for booster shots."

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