Question: What is a rapid molecular test? I was tested recently (with results in about 20 minutes), and the provider said it’s not PCR but more accurate than the antigen RDT. Is it worth finding/going to places where they offer rapid molecular tests, as opposed to antigen tests?

Answer: The Infectious Disease Society’s COVID-19 Real-Time Learning Network offers a great overview of rapid testing, which describes the differences between rapid molecular testing, antigen testing, and standard PCR testing. I took their synthesis and made a chart (Table 1) to show the similarities and differences. When it comes to which test to use, the Infectious Disease Society’s guidelines, “make no recommendations for or against using rapid tests (i.e., result time ≤ 1 hour) versus standard RNA testing in symptomatic individuals suspected of having COVID-19, citing knowledge gaps.”

As far as I can tell, when it comes to finding/going to places with specific test types, I think it depends on what you care most about — speed, accuracy, convenience, etc. Among the test types and based on what we currently know, rapid molecular tests seem to offer the best balance of speed, accuracy, and perhaps even comfort (re: sample collection). If it were me, that would likely be the test I’d aim to get. That said, it’s also really challenging to figure out what test is being offered by what provider. I might just go where the provider can see me the soonest (especially if I’m feeling unwell) or where I can be tested from my car (especially if I want to avoid sitting in a waiting room). What I’m saying is that a constellation of factors is at play for each individual going to get a test; ultimately, any of the three test types will get you the information you and your doctor need.

Related note: even though antigen tests fare less well at detecting true positives (moderate sensitivity), symptomatic individuals who test negative on the antigen test will then be given a PCR confirmatory test, per testing guidelines.

Table 1. Differences between Standard RNA/PCR tests, Rapid molecular tests, and rapid antigen tests.