- Virological tests (RT-PCR) are useful only for a very short period, at the start of infection, since they identify viruses when they enter the body. False negatives are observed (the best score is 70%). Even a positive test remains difficult to interpret, since the actual presence of viral material does not necessarily mean that it is still active.
- The serological tests are more reliable, but can only be used later than the previous one, because they are used to detect the antibodies which sign the defense of the organism against a virus (but it can be another virus than that of the Covid19). Few false positives, but produces a few false negatives. The performance of the test also depends on the type of test used (this is being evaluated).
It appears that all of these tests are only of interest to people with symptoms, but that it would be useless to consider systematic and generalized screening.
