Lickety-split antigen testing using a nasal swab with the BinaxNOW check turn out to be once ready to detect the Omicron variant at an urban neighborhood testing living, whereas other swabbing routes did no longer form as well, researchers came upon.
Sensitivity of the BinaxNOW assay for detecting PCR-certain conditions inside of a cycle threshold (Ct) of <30, indicating a bigger viral load, turn out to be once 74% (95% CI 53.7-88.9%) using a throat swab versus 97.7% (95% CI 87.7-99.9%) using the nasal swab alone, reported John Schrom, MPH, of the College of California San Francisco, and colleagues.
“The throat swab tremendously underperformed in comparison to the frequent nasal swab,” they wrote in a pre-print on medRxiv. “Even with the outstanding medical characteristic of pharyngitis in persons with omicron, our recordsdata argue against replacing nasal swabs with throat swabs for prognosis.”
Cheeks swabs were clearly the worst performing, though. Among these patients tested concurrently by task of nasal and cheek swabs, the sensitivity of cheek swab specimens turn out to be once 4.3%, and 9.0% for a Ct threshold <30, the authors mentioned, adding that "our recordsdata are compelling that a straightforward oral cheek swab would not develop detection of SARS-CoV-2."
Schrom’s community examined recordsdata from 4 days in January 2022 at a neighborhood testing living in downtown San Francisco. All ages were eligible. Lab assistants peaceful anterior nasal swabs for BinaxNOW antigen assessments alongside with RT-PCR assessments on the first 2 days of recordsdata assortment.
Nasal swabs and cheek swabs were peaceful from a cohort of 75 randomly chosen patients on the third day of recordsdata assortment and analyzed by task of RT-PCR and antigen testing. Nasal and oral tonsillar swabs were peaceful from a cohort of 115 randomly chosen patients on the fourth day.
General, RT-PCR and speedy antigen testing were performed on 731 samples all by the first 2 days of testing. Over three-quarters of patients were Hispanic/Latinx (77%). About 53% of patients were males, and 15% were youthful than 12. The most popular motivation for testing turn out to be once clearance for work (26%), adopted by diagnosed or suspected exposure (23%) and college requirement (18%).
About 41% of these samples tested certain by task of RT-PCR. Out of 186 other folks who tested certain by task of RT-PCR and had a Ct of <30, 177 tested certain with BinaxNOW. General, the short antigen check turn out to be once essentially the most mushy amongst samples with the lowest Ct values. Test sensitivity for Ct <30 turn out to be once 95.2% (95% CI 92-98%), but Ct <35 fell to 82.1% (95% CI 77-87%), and overall test sensitivity was 65.2% (95% CI 60-71%). BinaxNOW detected none of the 61 RT-PCR positive cases with a Ct>35.
Unsurprisingly, BinaxNOW had bigger sensitivity amongst symptomatic patients (97.6%, 95% CI 93-100%), though sensitivity amongst asymptomatic patients turn out to be once peaceful high (89.8%, 95% CI 79-96%).
Schrom disclosed no conflicts of interest.
One co-creator disclosed pork up from Gilead Sciences and Abbott.