Comparative Sensitivity of Rapid Antigen Tests for the Delta Variant (B.1.617.2) of SARS-CoV-2

Abstract

Rapid antigen tests (RATs) for COVID-19 based on lateral flow immunoassays are useful for rapid diagnosis in a variety of settings. Although many kinds of RATs are available, their respective sensitivity has not been compared. Here, we examined the sensitivity of 27 RATs available in Japan for the detection of the SARS-CoV-2 delta variant. All of the RATs tested detected the delta variant albeit with different sensitivities. Nine RATs (ESPLINE SARS-CoV-2, ALSONIC COVID-19 Ag, COVID-19 and Influenza A+B Antigen Combo Rapid Test, ImmunoArrow SARS-CoV-2, Fuji Dri-chem immuno AG cartridge COVID-19 Ag, 2019-nCoV Ag rapid detection kit, Saliva SARS-CoV-2(2019-nCoV) Antigen Test Kit, and Rabliss SARS-CoV-2 antigen detection kit COVID19 AG) showed superior sensitivity to the isolated delta variant. Although actual clinical specimens were not examined, the detection level of most of the RATs was 7500 pfu, indicating that individuals whose test samples contained less virus than that would be considered negative. Therefore, it is important to bear in mind that RATs may miss individuals shedding low levels of infectious virus.

Impaired detection of omicron by SARS-CoV-2 rapid antigen tests

“…In many countries, rapid antigen tests (RATs) for the detection of SARS-CoV-2 continue to be a central component of national testing strategies offering quick, inexpensive and laboratory-independent, point-of-care diagnostics. However, the evaluation by independent laboratories [14][15][16][17][18][19][20][21][22][23][24][25] and a Cochrane meta-analysis [26] have indicated a highly variable performance of RATs resulting in an ongoing controversy over these tests' utility for the detection of acute SARS-CoV-2-infected individuals in different settings relevant for clinical diagnosis and containment strategies.…”

Analytical sensitivity of six lateral flow antigen test kits for variant strains of SARS-CoV-2

“…The difference in the test LoDs like our study was observed in other reports. For example, a comparative study for the Delta variant reported from Japan showed quite similar findings [ 6 ]. While the most sensitive test was ESPLINE® and ImmunoArrow® in this report, LoDs of the QuickNavi™, Panbio™ and Rapid Antigen Test were 10-fold-higher, and that of ImmunoAce® was 100-fold higher.…”

Sensitivity of rapid antigen tests for Omicron subvariants of SARS‐CoV‐2

“…Second, RNA levels based on RT‐qPCR were not used to represent the virus amounts. Since RNA levels are correlated with infectious virus titers, 15 this would not affect the interpretation of the results within this paper, but might make it difficult to compare our results with those in other papers. Third, prototype isolates such as Wuhan‐Hu‐1 2019 were not included as a baseline.…”

“…Although the sensitivity of RATs is lower than that of RT‐qPCR, 2–9 RATs with a short turnaround time can help improve diagnosis. To this end, we and others previously compared the sensitivity of RATs and found that most RATs show similar sensitivity against ancestral SARS‐CoV‐2, SARS‐CoV‐2 possessing the D614G substitution in its S protein, and the delta variant (lineage B.1.617.2) 9–15 . RAT performance has also been evaluated for Omicron variant detection, including BA.1 and BA.2 16–22 .…”