Clinical diagnostics firm Beckman Coulter has launched its semi-quantitative assay, Access SARS-CoV-2 IgG II, which can measure a patient’s relative level of antibodies in response to a previous Covid-19 infection.

The assay helps clinicians to establish a baseline to analyse an individual’s immune response to the virus based on a numerical value and evaluate relative changes over time.

It can also aid researchers in estimating the levels of IgG antibodies required to be considered protective.

By measuring the IgG antibodies directed to the receptor-binding domain of the spike protein of the coronavirus in response to a previous infection, the assay delivers a numerical result in Arbitrary Units (AU) from 2-450AU / mL.

Access SARS-CoV-2 IgG II test also provides a qualitative result for SARS-CoV-2 IgG antibodies.

Beckman Coulter will submit an application to the US Food and Drug Administration (FDA) for Emergency Use Authorisation (EUA) of the assay.

The company will start shipping the assays to its customer base throughout the US and make them available to markets accepting the CE Mark before the end of the year.

Beckman Coulter chief medical officer Shamiram Feinglass said: “Having a clearer picture of the immune response to SARS-CoV-2 plays an important role in the fight against Covid-19, especially before a vaccine is widely available.

“While it’s unknown how long antibodies persist following infection, and if the presence of antibodies confers protective immunity, having a quantifiable baseline is a critical step towards furthering the understanding of the adaptive immune response to SARS-CoV-2 in individuals over time.”

In a study with 1,448 samples collected from donors in the US and France before December last year, the test has a confirmed 96% positive per cent agreement at eight to 14 days post symptom onset.

The assay can be used in Random Access Mode (RAM) and easily integrated into existing workflows without batch processing.