In a current research printed within the medRxiv* preprint server, researchers evaluated the diagnostic efficiency of a coronavirus illness 2019 (COVID-19) antigen take a look at throughout the current surge brought on by the extreme acute respiratory syndrome coronavirus-2 (SARS-CoV-2) Omicron variant.
With the emergence of SARS-CoV-2 Omicron, international COVID-19 circumstances have soared to new report highs, and the BA.1 and BA.2 sub-lineages have turn into predominant by early 2022. Antigen assessments are helpful diagnostic instruments to detect infectious illnesses as a result of they’re reasonably priced, easy, and supply sooner outcomes.
SARS-CoV-2 antigen assessments have been beneficial for asymptomatic and symptomatic people, significantly if the nucleic acid amplification testing is restricted or the viral prevalence exceeds 5%. Though it’s believed that diagnostic efficiency of antigen assessments is presumably preserved for SARS-CoV-2 Omicron, the sensitivity to the variant has been reportedly impaired for 9 completely different assessments.
In regards to the research
Within the current research, researchers prospectively examined the diagnostic efficiency of the QuickNavi-COVID-19 antigen take a look at, evaluating it to the reverse-transcription polymerase chain response (RT-PCR) take a look at outcomes. The research was carried out from December 28, 2021, to February 16, 2022, and samples had been collected at a drive-through web site at Tsukuba Medical Middle Hospital (TMCH).
Two samples had been collected from every particular person for antigen and RT-PCR assessments. Antigen testing was carried out instantly on the web site. RT-PCR was carried out utilizing an in-house methodology and one other methodology by the Nationwide Institute of Infectious Illnesses (NIID) within the TMCH microbiology division. To account for the discrepancy between outcomes from in-house RT-PCR and NIID strategies, further analyses had been carried out utilizing Xpert Xpress SARS-CoV-2 and GeneXpert system.
Furthermore, constructive samples had been topic to genome sequencing and SARS-CoV-2 variant evaluation. As well as, a supplemental analysis of eight completely different a lot of QuickNavi-COVID-19 antigen and QuickNavi-Flu + COVID-19 antigen take a look at was carried out throughout a non-surge interval (November 2021 – January 2022). This was carried out to estimate false positivity for SARS-CoV-2 detection.
Nasopharyngeal swab samples had been obtained from 1073 people, of which 154 had been asymptomatic, and the remaining had been symptomatic. The median time from symptom onset to sampling was two days. Total, 411 samples had been constructive for SARS-CoV-2 utilizing the NIID-developed methodology, and 6 discordant outcomes had been noticed between in-house and NIID strategies. When examined with GeneXpert System, these six had been discovered SARS-CoV-2-positive; subsequently, the overall variety of constructive samples was 417.
The QuickNavi antigen take a look at was 94.2% delicate and 99.5% particular, with constructive and damaging predictive values of 99.2% and 96.5%, respectively. The sensitivity and specificity for symptomatic people had been 94.3% and 99.8%, respectively, whereas, for asymptomatic people, it was 93.1% (sensitivity) and 98.4% (specificity). The bottom sensitivity (47.4%) was famous for PCR-positive samples with cycle threshold (Ct) values of 30 or above.
Throughout the non-surge interval, no pattern examined constructive for SARS-CoV-2 with RT-PCR testing within the supplemental evaluation. The researchers carried out 1200 assessments (QuickNavi COVID-19 and Flu + COVID-19 antigen assessments) with 400 swab samples and located zero false positives. Genome evaluation of 185 samples revealed that 140 samples had BA.1.1.2 variant, 21 samples contained BA.2.3 variant, and two every had been BA.2 and BA.1.1.1 variants. Total, greater than 85.9% of samples had been of Omicron BA.1 sub-lineage, 12.4% of BA.2 sub-lineage, and 1.6% had been of B.1.617.2 (Delta) variant.
The researchers famous that greater than 90% of PCR-positive samples had been constructive with QuickNavi antigen testing. These findings indicated that the antigen take a look at was delicate sufficient to detect BA.1 and BA.2 variants, the 2 main sub-lineages of SARS-CoV-2 Omicron. Beforehand, the authors evaluated the identical throughout the SARS-CoV-2 Delta wave and located 88.3% sensitivity for symptomatic people and 69.4% for asymptomatic topics.
The diagnostic efficiency was barely higher throughout the Omicron wave, plausibly as a result of larger proportion of symptomatic topics or excessive viral load among the many contaminated people. Regardless of the encouraging outcomes, some research limitations embody the small pattern dimension of asymptomatic people and all samples collected at one middle. For PCR testing, samples had been frozen and transported later, affecting the outcomes.
Additional, solely nasopharyngeal swab samples had been analyzed however not anterior nasal samples. In conclusion, the research demonstrated that the QuickNavi antigen take a look at had ample diagnostic efficiency to detect SARS-CoV-2 Omicron BA.1 and BA.2 sub-variants from nasopharyngeal swabs.
medRxiv publishes preliminary scientific studies that aren’t peer-reviewed and, subsequently, shouldn’t be thought to be conclusive, information scientific apply/health-related habits, or handled as established data.