EKF Launches One of the First Tests to Precisely Measure Levels of COVID-19 Neutralizing Antibodies

EKF Diagnostics (Cardiff, Wales, UK) has introduced the new Kantaro COVID-SeroKlir SARS-CoV-2 IgG antibody test kit which is one of the first tests to precisely measure levels of COVID-19 neutralizing antibodies in individuals.

The best-in-class serologic COVID-19 assay is based on technology developed by clinicians at the Icahn School of Medicine at Mount Sinai Health System in New York in partnership with RenalytixAI, a spinout company from EKF Diagnostics. Unlike other antibody tests, the Kantaro COVID-SeroKlir SARS-CoV-2 IgG antibody test kit determines both the presence and specific quantities of human IgG antibodies to the SARS-CoV-2 virus. This enables a broad range of COVID-19 applications, such as delivering vital knowledge for advancing the understanding of protective immunity, assessing vaccine response and accelerating therapeutic treatments.


Being a two-step enzyme-linked immunosorbent assay (ELISA) ensures COVID-SeroKlir’s accuracy. The ELISA’s initial plate screens for RBD positive or negative samples, while the second plate provides a quantitative result of the antibody titer/concentration for the full-length spike protein. As the kit uses standard methods and equipment, it is easily operated without need for scaled equipment or special environments and contains components to test 630 patient samples.

COVID-SeroKlir has been validated on a highly diverse cohort of more than 75,000 patients, including over 30,000 who were diagnosed with COVID-19; this is more than any other COVID-19 test. In addition, the test has been independently verified by peer reviewed journals, including Nature and Science, as well as the US National Institutes of Health (NIH). It has demonstrated 98.8% sensitivity and 99.6% specificity for detecting SARS-CoV-2 specific IgG antibodies against two SARS-CoV-2 virus antigens, the full-length spike protein and its receptor-binding domain (RBD). This confirmed accuracy means false positives and false negatives are minimized. The Mount Sinai study also demonstrated that over 90% of infected individuals with mild-to-moderate COVID-19 experience robust IgG antibody responses against the viral spike protein. In addition, these COVID-19 neutralizing antibody levels were confirmed to be relatively stable during the first five months after infection.

The high performance quantitative COVID-SeroKlir kit has received FDA Emergency Use Authorization (EUA) and is CE marked. EKF holds exclusive rights to market and distribute the Kantaro COVID-SeroKlir kit in the UK and Germany, and non-exclusive rights in the rest of Europe.

“Quantitative IgG antibody testing can provide important support for determining public health strategies, informing healthcare decision making, and verifying the effectiveness of vaccines as they become available,” said Julian Baines, CEO of EKF. “It is also an essential component of a general health check to determine past COVID-19 infections. This is because COVID-19 has been linked with an increased risk of potentially life-threatening complications, including lung, kidney, and cardiovascular disease. With the capacity to manufacture up to 10 million tests per month, EKF is well placed to drive rapid availability of COVID-SeroKlir kits to a broad range of laboratories for immediate operation without needing specialized testing equipment.”