In short RT-PCR is the tests they use for detection of SARS-CoV-2 - the novel coronavirus that is causing COVID-19.
 I have been wondering for a long time how accurate the tests actually is, but couldn't find a straight answer; then have stumbled across document titled 'Impact of false-positives and false-negatives in the UK’s COVID-19 RT-PCR testing programme' which attempts to estimate accuracy of the tests. Although it does mention false positives, as expected, the government is more interested in false negatives (obviously).
 Let's focus on false positives: 
 The document estimates current false positive rate as UNKNOWN (reminder: or lives are more or less governed by this test). However it then gives estimate of false positives as 0.8-4.0 - median of 2.3% based on previous experience with RT-PCR. 
 What does that mean? Simply that as many as 100% of reported positive cases could be false positives ! 
 Here is why, according to the document, out of 100,664 tests 98.4% were negative which leaves us with 1.6% or 1570 positives. Now if the estimated false positive rate is applied then that means between 805 and 4026 (0.8 to 4%) could be false positives which means accuracy of a positive result ranges form 0% to max 51%. 
 Common sense would dictate that the virus is mostly gone and increased testing generates a large number of false positives. Are we being scammed? For reference: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/895843/S0519_Impact_of_false_positives_and_negatives.pdf