COVID RT PCR

Function

The COVID-19 Reverse Transcription Polymerase Chain Reaction (RT-PCR) test is the 'gold standard' for detecting the SARS-CoV-2 virus. It works by amplifying specific genetic sequences (RNA) of the virus. Because the PCR process creates millions of copies of the viral genetic material, it can detect even minute amounts of the virus in a patient's system, making it far more sensitive than rapid antigen tests.

Why it is Ordered

This test is ordered to diagnose an active COVID-19 infection in symptomatic individuals or those with known exposure. It is also used for screening in high-risk settings (hospitals, nursing homes), for international travel clearance, and for pre-operative clearance. Unlike antibody tests, the RT-PCR tells you if you are currently infected, not if you had a past infection.

Associated Conditions

• COVID-19 (SARS-CoV-2 Infection): The primary target of the assay.
• Pneumonia/ARDS: Complications arising from severe viral replication in the lower respiratory tract.
• Long COVID: Patients may occasionally remain PCR-positive for extended periods, though this does not always imply infectivity.

The Testing Process

The sample is typically collected via a nasopharyngeal or oropharyngeal swab. In the lab, the RNA is extracted and converted to DNA using the enzyme reverse transcriptase. The DNA is then amplified through thermal cycling. If the virus is present, a fluorescent signal is generated that exceeds a specific threshold (the Cycle Threshold or Ct value).