astuteman wrote:A PCR test on its own can't.
But it can if you use the test sample to run a DNA sequence.
The Lab our company uses for its PCR tests does this routinely on every PCR test.
But that's because we invested in the cost of a DNA sequencer
I doubt that the lab is doing whole genome sequencing on every test. There is little clinical or surveillance purpose for this and it would be prohibitively expensive.
But also, one of the quirks of Omicron is that one of the mutation deletions results in what is being called an S-gene dropout. The PCR tests have multiple gene targets, but a specific gene is consistently "dropping out" during PCR testing for Omicron (not occurring for other variants) if that target used in the test. So, if the specific PCR test used is targeting this specific gene, then the test result may give an indication that a positive PCR may be Omicron. It was this anomaly that led the South Africans to search for the new variant, and how several countries are now identifying Omicron positives (including UK and Netherlands that have gone back and rechecked prior tests).
While the lab will give you a positive or negative result, the positive is defined by multiple target genes being detected.
