GLENS FALLS, N.Y. (NEWS10) — With a rise in COVID cases continuing and more people looking to get tested, there are some key differences between the two types of tests that detect the coronavirus: PCR and rapid antigen.

“PCR, which is polymerase chain reaction, that’s when you’re actually looking for the genetic material of the pathogen itself, so you’re looking for the bug’s genetic makeup. Antigen testing, which is the other type of diagnostic testing, looks for the byproduct of the pathogen,” Hillary Alycon, Director of Quality Management and Infection Prevention at Glens Falls Hospital explained.

For the most accurate results, medical experts say go with a PCR, which also have a longer turnaround time.

“PCR tests can detect the virus’ presence up to 48 hours prior to your symptom onset,” said Alycon.

Rapid testing may also be less effective at picking up the now dominant omicron variant. Last month, the FDA said early data suggests antigen testing may have reduced sensitivity to the spreading variant.

Despite this, Alycon says these tests are still valuable, especially if you’re symptomatic, “So if you get a rapid test, a positive test at home, you know to self-isolate, you know to seek further testing to get that confirmation.”

However, if a rapid test comes back negative when you’ve been exposed and are showing symptoms, Alycon says you should be skeptical, as it could be a false negative.

In terms of when to get tested, Alycon suggests five days after initial exposure and immediately if you begin displaying symptoms. She also stresses that it’s important to get tested if you are symptomatic, rather than just quarantining without confirmation, to know if you have COVID or something else.

As cases have continued to rise, more testing facilities are opening in the Capital Region. The new site at Crossgates Mall, which opened Tuesday, is offering both rapid antigen and PCR testing.

Meanwhile, additional state sites at SUNY campuses will open Friday, including at UAlbany, where saliva-based testing will be offered.