WHAT TYPE OF COVID TESTS ARE MOST ACCURATE? Whether you are testing because of an upcoming family visit, travel, or because you have symptoms, what method of testing is best?
Nasopharyngeal swabs are the most effective means of detecting COVID-19 infection, offering detection rates of 92 to 100 percent. That’s the conclusion of Cornell University (USA) researchers.
COVID test accuracy
The scientists obtained samples from patients; more specifically, they got four types of specimens:
- Nasopharyngeal swabs (the Q-tip-like collector goes deep into your nose)
- Anterior nares swabs (front of the nostril)
- Sublingual swabs(under the tongue)
The researchers obtained the samples from individuals with symptoms, individuals without symptoms, and subjects who had recovered from illness.
Covid detection rates by test type
Let’s look at the results by test type:
The nasopharyngeal samples had the best detection rate, from 92 to 100 percent. This high detection rate seems logical, as the COVID virus replicates in the uppermost portion of the nose.
Samples from the front of the nostril and saliva proved fairly good, too; about 92 to 96 percent effective for patients with symptoms. On the other hand, when patients had no symptoms, these approaches worked 75 to 92 percent of the time.
Under the tongue sampling proved suboptimal, with detection rates of only 40 to 60 percent for patients with symptoms and 25 to 42 percent for those without symptoms.
Overall, detection rates appeared highest for those with symptoms, ranging from 92 to 100 percent. The detection rate dropped to 75 to 96 percent for those without symptoms. Finally, once a patient no longer had symptoms, detection proved challenging.
I find nasopharyngeal swab tests — wherein the swab is sent far back inside the nostril — dreadful. But this approach is more effective at finding COVID-19 than are swabs put just inside the nose, swabs under the tongue, or saliva tests.
Fortunately, samples obtained from the front of the nose are reasonably accurate (and easier to perform). Study researcher Diego Diel offers this relevant observation:
“We were surprised at the short time in which infectious virus was detected. The data aligns with current US Centers for Disease Control guidelines and its decision to decrease patient isolation periods from an initial 14-day period to 10 and ultimately to five.”
Here’s a piece I wrote earlier on long COVID: