Determining the Reliability of Rapid SARS-CoV-2 Antigen Detection in Fully Vaccinated Individuals

The effect of ivermectin on the viral load and culture viability in early treatment of nonhospitalized patients with mild COVID-19 – a double-blind, randomized placebo-controlled trial

“…Although negative PCR is defined in Israel with Ct > 40 and borderline with Ct > 35, it was found that reaching this level may take a few weeks. In contrast, at an early stage of the pandemic, significant evidence showed that a noninfectious state is usually achieved at Ct level > 30 Bullard et al, 2020 ;Gilad et al, 2021 ;Poopalasingam et al, 2022 ;Wölfel et al, 2020 ), and therefore isolation time in Israel was changed in September 2020 and was reduced to 10 days without looking for complete negative results. Therefore, we defined a negative test at a noninfectious level as measured by RT-PCR of Ct values > 30 (less than 3.4 × 10 4 viral copies per reaction, equal to less than 10 6 copies/ml).…”

Performance and application evaluation of SARS‐CoV‐2 antigen assay

“…39 The overall specificity of the COVID-19 antigen reagent was 99.7%. 39 The sensitivity of the Panbio™ COVID-19 assay is even worse for the diagnosis of COVID-19 due to vaccination breakthrough Omicron infection compared with Delta (the sensitivity is 36.1% vs. 67.7%). 40 In summary, the SARS-CoV-2 mutant reduced the virus detection rate of the SARS-CoV-2 antigen reagent, especially the SARS-CoV-2 mutant that escaped from the vaccines.…”

“…Stratified by C t values, the sensitivity of the SARS‐COV‐2 antigen assay was 100.0%, 94.4% and 81.1% for C t ≤ 20 ( n = 18), C t ≤ 25 ( n = 36) and C t ≤ 30 ( n = 53), respectively. Samples with C t values ≥ 30 ( n = 23) could not be detected 39 . The overall specificity of the COVID‐19 antigen reagent was 99.7% 39 .…”

“…Samples with C t values ≥ 30 ( n = 23) could not be detected 39 . The overall specificity of the COVID‐19 antigen reagent was 99.7% 39 . The sensitivity of the Panbio™ COVID‐19 assay is even worse for the diagnosis of COVID‐19 due to vaccination breakthrough Omicron infection compared with Delta (the sensitivity is 36.1% vs. 67.7%) 40 …”

“…The performance of the SARS‐CoV‐2 antigen assay in vaccine‐escaped COVID‐19 patients is also a concern. During the delta wave, a total of 692 samples from vaccinated individuals were tested for COVID‐19 nucleic acid and antigen, among which 76 samples (11.0%) tested positive for SARS‐CoV‐2 by RT–qPCR and 45 samples (6.5%) tested positive by Standard Q COVID‐19 AGT 39 . Stratified by C t values, the sensitivity of the SARS‐COV‐2 antigen assay was 100.0%, 94.4% and 81.1% for C t ≤ 20 ( n = 18), C t ≤ 25 ( n = 36) and C t ≤ 30 ( n = 53), respectively.…”