Further to publishing evaluation criteria for serological tests for antibodies against SARS-CoV-2 (available here), the French High Health Authority (HAS) published on 18 May 2020 its opinion on the use of rapid serological tests (including self-tests) and an educational paper on Covid-19 coronavirus serological tests.
The HAS indicated that while all serological tests used for the diagnosis of Covid-19 coronavirus attempt to detect antibodies in the blood, they do not all have the same characteristics and uses. There are two main categories:
- Automated tests, which are performed from a blood sample and require a suitable technical platform to analyse the samples.
- Rapid unit tests, which are performed from a drop of blood taken from the fingertip and return a result within a few minutes.
The HAS considers that these tests do not yet have a place in the identification of persons protected against the Covid-19 coronavirus. However, by identifying persons who are or have been infected by the virus, serological tests are useful in the epidemiological surveillance of the disease and in the wider diagnostic strategy, in addition to virological tests, which test for the virus rather than antibodies and remain the first-line tests for the diagnosis of the acute phase of Covid-19.
The HAS previously defined the populations for which diagnosis by means of an automated serological test would be relevant. With these publications, the HAS completes its work by defining the indications for rapid diagnostic tests (RDTs), rapid diagnostic orientation tests (RDOTs) and self-tests. The HAS recommends using RDTs and RDOTs in the same populations as the automated tests:
- For back-up diagnosis of symptomatic patients, in case of a negative virological test but symptoms suggestive of Covid-19.
- Among healthcare personnel or group accommodation establishments that have been in contact with the virus.
- For epidemiological investigations.
However, within that use, the HAS recommends the use of RDOTs in a more restricted field than RDTs and automated tests. That is, only for care and group accommodation staff and for symptomatic patients without signs of severity if they have difficulty accessing a medical biology laboratory, but not in hospital. The HAS considers that RDOTs are not a substitute for medical biology laboratory tests such as serological ELISA (an enzyme-based test for target proteins such as antibodies) or RDT, which would be required to confirm a positive RDOT.
Regarding self-tests, the HAS has identified two major obstacles: the lack of real-life data and uncertainty about their use (particularly the difficulty in patients reading and interpreting the results). Accordingly, the HAS considers that it is premature to recommend the use of serological self-tests for the diagnosis of Covid-19.
A prior version of this post was originally published by the same authors in Practical Law – Life Sciences, June 2020 Issue (Thomson Reuters).