The Peter Doherty Institute has produced its Final Report. It...

The Peter Doherty Institute has produced its Final Report. It was engaged to undertake a post-market assessment of the COVID-19 rapid test technology in order to determine its best use. Its task was not to validate the performance claims of individual test kits on the TGA’s list.

Using three representative tests the Institute has concluded that POC devices are not suitable for clinical use in detecting the acute presence of the disease. Understandably, since the kits have not yet been employed for immunity surveys it reaches no conclusion on that possible use.

“Our findings strongly suggest that PoCT devices should not be used in the diagnosis of acute COVID-19, and have limited, if any, role in clinical management of individual patients The role of PoCT in population-level serosurveys remains to be seen….”

The PCR ‘swab’ test methodology involves an amplification process that gives it high sensitivity soon after symptoms appear. The test retains its high sensitivity during the acute period of the infection but disappears post-infection along with the virus.

Antibodies appear around the same time and build up as the infection progresses. Lacking amplification the sensitivity of the POC test only builds up at the corresponding rate. Its sensitivity reaches a maximum late in the acute phase, which is retained well into post-infection while the antibodies remain. The POCT degree of sensitivity therefore is time dependent and has a lower probability of giving a positive result early in the infection the way a PCR test can.

The obvious value of the POCT devices lies in their use to detect the presence of antibodies post-infection, with the implication of indicated immunity. In doing so it is important that those antibodies have not derived from a different virus. The high specificity of 99.6% quoted by Wondfo has been confirmed as 99.2% in a survey published by Univ California.

Journalists (and governments and others) have made the mistake of believing that because the tests are not suitably sensitive at the early infection stage they therefore are a failure. That same conclusion could be reached from the Doherty findings quoted above if that is thought to be the test’s purpose.

It is a TGA condition that supply of the kits can occur only if individual sponsors provide further information supporting the performances of their device. The Doherty won’t be doing so. Hence the request on the Cellmid website for volunteers likely to have antibodies.

The current trading suspension appears to be directed at preventing shareholders from making the same mistake as the journalists. It will be interesting to see the content of the announcement that accompanies its lifting.