This RT-PCR test is very sensitive for the presence of SARS-CoV-2, with 98% of tests providing either a positive or a negative result, and only 2% of tests providing an inconclusive result. The test can detect fewer than 10 copies of viral genes per milliliter of saliva, and can detect the presence of virus in the saliva within 2 days of infection and up to 28 days after infection. Across all known gene sequences of SARS-CoV-2, the test detects the ones in the genes of interest ~100% of the time, making it highly sensitive and specific for those genes.
The false positive and false negative rates for this are both 1%. A “false positive” is a result that is positive that actually should have been negative, and a “false negative” is a negative result that should have been positive. With a false positive and negative rate of 1%, this means that 99% of the time, a positive or negative result is the actual result after just a single test. To put this in context, a lot of COVID-19 tests have a low false positive rate, but the false negative rates of some nasopharyngeal swab-based tests can be as high as 25-35%.