Sequencing Used to Identify Delta, Other Coronavirus Variants

Tests that detect current infections with SARS-CoV-2, the virus that causes COVID-19, are known as viral tests. There are two types: a Nucleic Acid Amplification Test, or NAAT, and an antigen test. 

Many of the NAATs use a molecular biology technique known as the polymerase chain reaction, or PCR, to detect even a very tiny amount of the virus in a specimen.

The PCR test takes advantage of some natural features of biology to essentially scan through all of the RNA present in a sample — such as a nasal swab — and search for the presence of coronavirus RNA. 

The Centers for Disease Control and Prevention NAATs “are unlikely to return a false-negative result of SARS-CoV-2,” and it recommends only laboratory-based NAATS, the most saliva tests aren’t as optimal as those using swabs of the nose or nasopharynx (upper throat behind the nose).