- Reference laboratory diagnostic tests for SARS-CoV-2 are carried out by means of genome amplification tests (RNA) in a polymerase chain reaction in real time, preceded by reverse transcription (rRT-PCR).
- Exudate from the nasopharyngeal and oropharyngeal collected through a swab.
72 hours (3 working days)
Who should be tested?
The test should be done by people with symptoms of COVID-19 or who have had contact with confirmed cases of COVID-19. When can I take the test? In general, the test can be performed during the pre-symptomatic or symptomatic phase. It is based on the detection of the SARS-CoV-2 genome (RNA) by real-time rRT-PCR techniques in exudates from the nasopharynx and oropharynx. The viral load is higher in the first days of infection and starts to decrease after 15 days after infection.
What is the specificity and sensitivity of these tests?
The real-time RT-PCR test used is 100% specific and does not cross-react with other human coronaviruses. For molecular diagnosis, we use two different SARS-CoV-2 proteins as targets.
The sensitivity of the molecular test depends on the viral load present in the sample. The viral load is maximal 5-7 days after infection and from then on it starts to decrease, becoming diminished 15 days after infection.
In order to assess the specificity and sensitivity of our rRT-PCR molecular tests and quality procedures implemented, the laboratory was subjected in May 2020 to an international blind external evaluation of the QCMD 2020 Coronavirus Outbreak Preparedness EQA Pilot Study (CVOP20).
In this external evaluation of QCMD we obtained the maximum score with 0% of errors in samples considered ‘core’ and in educational samples. Thus, we obtained 100% specificity and a sensitivity to detect 1 to 5 viral particles/reaction.