On 25 September 2020, the French National Authority for Health (HAS) issued a favourable opinion on the use of antigenic tests on nasopharyngeal swabs in people who present symptoms of Covid-19. The HAS specified the required performance: a minimum sensitivity of over 80% and a minimum specificity of over 99%. The HAS also acknowledged that the circulation of the virus has accelerated, and it is essential to offer everyone optimal care and to break the chain of infection to stem the epidemic.
In France, the RT-PCR test on nasopharyngeal swabs remains the reference test for the detection of the SARS-CoV-2 virus. However, the epidemic situation and the positive performance of antigenic tests led the HAS to issue an opinion regarding different tests for the following three clinical situations:
- Patients with symptoms. If the RT-PCR test cannot be obtained within 48 hours, the HAS recommends performing an antigen test within the first four days after the onset of symptoms. The HAS restricts the window of use of antigenic tests from seven to four days compared to its first opinion of 24 September 2020 because this is the period during which the tests are most effective. Given the excellent specificity of these tests, the HAS considers it unnecessary to confirm positive antigenic tests with an RT-PCR test. For patients at risk of developing a serious form of the disease (such as patients over 65 years of age or presenting at least one risk factor), the HAS recommends confirming negative antigenic test results by RT-PCR.
- People without symptoms who are not contact persons. The HAS recognises the value of using antigenic tests in large-scale screening operations targeting populations where the risk of infection is higher than in the general population. This may include populations that live, study or work in confined spaces.
- Symptom-free contact persons identified individually or within a cluster. The HAS does not yet have the necessary data to recommend the use of antigenic tests for asymptomatic contact persons who are identified individually or within a cluster. The virological RT-PCR test remains the test to be used in this situation. The HAS is awaiting the results of several ongoing studies which should provide answers to these questions in the near future.
The HAS is continuing to monitor the tests and sampling methods available or under development for the detection of SARS-CoV-2. It will update its work as soon as new data become available.
A prior version of this post was originally published by the same authors in Practical Law – Life Sciences, November 2020 Issue (Thomson Reuters).