Avacta upbeat on initial data for Covid-19 rapid test study

Biotherapeutics and reagents developer Avacta Group has received the first data for its SARS-CoV-2 rapid antigen test from ongoing clinical studies in Europe and the UK, it announced on Tuesday.

The AIM-traded firm said the data showed “excellent” performance of the test in identifying patients with an infectious viral load, and no false positive results.

It said its SARS-CoV-2 rapid antigen test was developed to identify infectious individuals, so that they could isolate promptly and reduce the spread of Covid-19.

A recent report from the Liverpool Covid SMART Pilot Study indicated that individuals with Covid-19 infection had a significant chance of infecting their contacts if they had a viral load measured by PCR, called the cycle threshold (Ct) value, of about 25 or lower.

The Ct value indicates how many PCR cycles are required to amplify the viral RNA so that it can be detected, and a lower Ct value indicates a higher viral load.

Avacta said the initial evaluation of its lateral flow rapid antigen test with clinical samples was carried out at two sites, one in the European Union and one in the UK, using patient samples with viral loads confirmed by PCR.

A total of 30 positive samples were tested with Ct values of 26 and below, with half of those in the range of 22 to 26, as the lateral flow test identified 29 of those correctly as positive.

That indicated a clinical sensitivity of 96.7% for samples with a Ct value below 26, the company said.

Out of a total of 26 negative samples tested with the lateral flow device, the test correctly identified all 26 as negative, giving a clinical specificity of 100%.

High specificity is “critical” for a lateral flow test for mass screening, Avacta explained, so that large numbers of false positives are not generated, which would create a “major burden” on follow-on testing resources, and result in a significant socioeconomic cost of unnecessarily isolating people.

On the basis of that initial data, the firm said it would now progress to a full clinical validation with a larger number of patient samples to CE-mark the test for professional use, aiming to bring the test to market in Europe around the end of the first quarter.

“On the basis of these initial clinical studies, the lateral flow test shows very good sensitivity in the infectious range of viral loads including at the lower infectious loads with Ct values of 23-26 which compares very favourably with the data reported in the Liverpool Covid SMART Pilot Study report,” said chief executive officer Dr Alastair Smith.

“These data from the first clinical studies will allow us to quickly progress with confidence into the full clinical validation of the test, manufactured at scale, at our clinical trial sites in the UK and the EU.

“I am confident that these data will accelerate our commercial discussions regarding the roll-out of the test when it is approved for professional use.”

At 0921 GMT, shares in Avacta Group were up 21.55% at 187.8p.