The widespread and long-lasting effect of the COVID-19 pandemic has called attention to the significance of technological advances in the rapid diagnosis of SARS-CoV-2 virus. This study reports the use of a highly stable buffer-based zinc oxide/reduced graphene oxide (bbZnO/rGO) nanocomposite coated on carbon screen-printed electrodes for electrochemical immuno-biosensing of SARS-CoV-2 nuelocapsid (N-) protein antigens in spiked and clinical samples. The incorporation of a salt-based (ionic) matrix for uniform dispersion of the nanomixture eliminates multistep nanomaterial synthesis on the surface of the electrode and enables a stable single-step sensor nanocoating. The immuno-biosensor provides a limit of detection of 21 fg/mL over a linear range of 1-10 000 pg/mL and exhibits a sensitivity of 32.07 ohms·mL/pg·mm2 for detection of N-protein in spiked samples. The N-protein biosensor is successful in discriminating positive and negative clinical samples within 15 min, demonstrating its proof of concept used as a Clarity COVID-19 Rapid Test accuracy rapid antigen test.
Communities and testing for COVID-19
- The response to the COVID-19 epidemic requires people to undertake actions such as mask-wearing or vaccination that also confer benefits to the whole community, and therefore, are akin to public good contributions.
- This is the case also for participation to the mass testing that took place between November 18th and 25th, 2020 in the South Tyrol region of Italy, where 361,781 out of 500,607 (72.3%) eligible residents volunteered to take a COVID-19 rapid antigen test.
- We examine the community characteristics that are associated with higher testing rates. Our findings point to a number of key community determinants of people’s willingness to volunteer. Convenience and social capital were important factors.
- Beyond that, socioeconomic status and religiosity were also both positively related to greater testing, while childhood vaccinations refusal rates show a negative relationship.
Ultrasensitive assay for saliva-based SARS-CoV-2 antigen detection
- Widespread SARS-CoV-2 testing is invaluable for identifying asymptomatic/pre-symptomatic individuals. There remains a technological gap for highly reliable, easy, and quick SARS-CoV-2 diagnostic tests suitable for frequent mass testing. Compared to nasopharyngeal (NP) swab-based tests, saliva-based methods are attractive due to easier and safer sampling. Current saliva-based SARS-CoV-2 rapid antigen tests (RATs) are hindered by limited analytical sensitivity. Here, we report one of the first ultrasensitive, saliva-based SARS-CoV-2 antigen assays with an analytical sensitivity of <0.32 pg/mL, corresponding to four viral RNA copies/µL, which is comparable to that of PCR-based tests.
- Using the novel electrochemiluminescence (ECL)-based immunoassay, we measured the SARS-CoV-2 nucleocapsid (N) antigen concentration in 105 salivas, obtained from non-COVID-19 and COVID-19 patients. We then verified the results with a second, independent cohort of 689 patients (3.8% SARS-CoV-2 positivity rate). We also compared our method with a widely used point-of-care rapid test.
- In the first cohort, at 100% specificity, the sensitivity was 92%. Our assay correctly identified samples with viral loads up to 35 CT cycles by saliva-based PCR. Paired NP swab-based PCR results were obtained for 86 cases. Our assay showed high concordance with saliva-based and NP swab-based PCR in samples with negative (<0.32 pg/mL) and strongly positive (>2 pg/mL) N antigen concentrations. In the second cohort, at 100% specificity, sensitivity was also 92%. Our assay is about 700-fold more sensitive than the Abbott Panbio Rapid Test.
We demonstrated the ultrasensitivity and specificity assay and its concordance with PCR. This novel assay is especially valuable when compliance to frequent swabbing may be problematic.
Prevalence of Pfhrp2/3 gene deletions among false negative rapid antigen test results in central India
- The diagnosis of Plasmodium falciparum malaria is widely dependent on the P. falciparum histidine rich protein 2 (PfHRP2) antigens based rapid diagnostic tests. There are few possible factors like Pfhrp2 polymorphism, Pfhrp2 deletion and density of malaria parasite which can affect the sensitivity of the Pf-HRP2-based RDT. The primary objective of the investigation was to check whether the Pfhrp2 gene deletion is the primary cause of RDT false negative cases.
- Febrile patients from three districts of Chhattisgarh, India were screened for malaria during 2016-2017 by microscopy and RDT. All microscopy P. falciparum positive samples were validated by PCR. Microscopy positive and RDT negative samples were analyzed for the presence of Exon 2, across Exon 1-2, upstream and downstream of both the Pfhrp2 and Pfhrp3 genes fragment by PCR.
- Out of 203 screened samples, 85 were detected positive for P. falciparum malaria based on microscopy and PCR. Among these 85 P. falciparum positive samples, 4 samples were observed Pf-HRP2 RDT negative. Although, it signified that the RDTs used were reliable with sensitivity of 95.3% (81/85). 3/4 PfHRP2-RDT negative samples of the P. falciparum isolates exhibited complete deletion of Pfhrp2 and Pfhrp3 genes and one sample was found RDT false negative due to high parasite density.
- Pfhrp2 and Pfhrp3 deletions that result in false negative RDTs were uncommon in our setting. The continued monitoring of RDTS which results in false negative tests due to Pfhrp2/3 gene deletion is the need of the hour for an effective malaria elimination strategy.
OraSure InteliSwab Rapid Antigen Test performance with the SARS-CoV-2 Variants of Concern Alpha, Beta, Gamma, Delta, and Omicron
The emergence of SARS-CoV-2 in the human population and the resulting COVID-19 pandemic has led to the development of various diagnostic tests. The OraSure InteliSwab COVID-19 Rapid Test is a recently developed and FDA emergency use authorized rapid antigen-detecting test that functions as a lateral flow device targeting the nucleocapsid protein. Due to SARS-CoV-2 evolution, there is a need to evaluate the sensitivity of rapid antigen-detecting tests for new variants, especially variants of concern like Omicron.
In this study, the sensitivity of the OraSure InteliSwab Test was investigated using cultured strains of the known variants of concern (VOCs, Alpha, Beta, Gamma, Delta, and Omicron) and the ancestral lineage (lineage A). Based on dilution series in cell culture medium, an approximate limit of detection for each variant was determined.
Accu-Tell COVID-19 IgG/IgM Rapid Test |
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| GEN-B352-20tests | Accu test | 20 tests |
Accu-Tell COVID-19 IgG/IgM Rapid Test |
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| GEN-B352-40tests | Accu test | 40 tests |
COVID-19 IgG/IgM Rapid Test Kit |
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| UNCOV-20 | UnScience | 20T/kit |
Panbio™ COVID-19 IgG/IgM Rapid Test |
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| ICO-T402 | Abbott | 25 Tests/Kit |
Panbio™ COVID-19 Ag Rapid Test Device |
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| 41FK10 | Abbott | 25 Tests/Kit |
Panbio™ COVID-19 Ag Rapid Test Device (Nasal) |
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| 41FK11 | Abbott | 25 Tests/Kit |
SARS-CoV-2 Antigen Rapid Test Kit |
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| CoV2Ag-1 | UnScience | 1T |
SARS-CoV-2 Antigen Rapid Test Kit |
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| CoV2Ag-25 | UnScience | 25T/kit |
NOVATest Antigen Rapid Test Kit (For Single Use) (NOVA Test) |
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| nCov-500-01 | Atlas Link Technology | 1T |
NOVATest Antigen Rapid Kit (NOVA Test) |
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| nCov-500 | Atlas Link Technology | 20 Tests |
SARS-CoV-2 Rapid Antigen Test Nasal |
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| 9901-NCOV-03G | Roche Diagnostics | 25 Tests/Kit |
Human Streptococcus Pneumoniae (SP) Antigen Rapid Test Kit |
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| abx092096-20tests | Abbexa | 20 tests |
Avian Influenza Virus Antigen Rapid Test Kit (Colloidal gold) |
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| abx092015-40tests | Abbexa | 40 tests |
Coronavirus (SARS-Cov-2) Antigen Rapid Test Device (Saliva) |
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| IOV87952 | INVBIO | 20T/kit |
Newcastle Disease Virus Antigen Rapid Test Kit (Colloidal gold) |
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| abx092016-40tests | Abbexa | 40 tests |
Human Chlamydia Trachomatis Antigen Rapid Test Kit (Colloidal gold) |
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| abx092049-20tests | Abbexa | 20 tests |
Avian Influenza H5 Virus Antigen Rapid Test Kit (Colloidal gold) |
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| abx092014-40tests | Abbexa | 40 tests |
Avian Influenza H7 Virus Antigen Rapid Test Kit (Colloidal gold) |
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| abx092017-40tests | Abbexa | 40 tests |
COVID-19 Nucleocapsid recombinant antigen |
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| 00221-V-100ugvial | Virogen | 100 ug/vial |
TruStrip RDT Anthrax Protective antigen 83 (PA83) Rapid Test cards, 25/pk |
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| 800-100-RDT-25 | Alpha Diagnostics | 1 pk |
2019-nCoV IgG/IgM Rapid Test Cassette (Whole Blood/Serum/Plasma) |
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| GEN-402-25tests | All test | 25 tests |
TruStrip RDT Zaire Ebola Virus antigen (GP) rapid test (visual results in 2-10 mins), 10 cassettes/pk |
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| AE-320805-RDT-10 | Alpha Diagnostics | 1 pk |
COVID-19 Nucleocapsid recombinant antigen C-terminal domain |
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| 00227-V-100ugvial | Virogen | 100 ug/vial |
Melamine Rapid Test Kit |
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| abx092011-50tests | Abbexa | 50 tests |
Brucella Antibody Rapid Test Kit |
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| abx092069-40tests | Abbexa | 40 tests |
COVID-19 Spike-E-M Immunodominant regions recombinant antigen |
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| 00220-V-100ugvial | Virogen | 100 ug/vial |
TruStrip RDT Canine distemper virus (hardpad disease) antigen rapid test card, results is 2-10 mins, 50 cards/pk |
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| RV-501200-RDT | Alpha Diagnostics | 1 pk |
NOVATest IgG/IgM Antibody Rapid Test Kit (NOVA Test) |
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| UNCOV-40 | Atlas Link Technology | 40 Tests |
Melamine (MEL) Rapid Test Kit |
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| abx092057-50tests | Abbexa | 50 tests |
Quinolones (QNs) Rapid Test Kit |
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| abx092065-40tests | Abbexa | 40 tests |
Salbutamol (SAL) Rapid Test Kit |
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| abx092060-50tests | Abbexa | 50 tests |
Quinolones (QNs) Rapid Test Kit |
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| abx092067-40tests | Abbexa | 40 tests |
Clenbuterol (CLE) Rapid Test Kit |
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| abx092058-50tests | Abbexa | 50 tests |
Ractopamine (RAC) Rapid Test Kit |
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| abx092059-50tests | Abbexa | 50 tests |
Tetracycline (TCs) Rapid Test Kit |
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| abx092063-50tests | Abbexa | 50 tests |
Sulfonamides (Sas) Rapid Test Kit |
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| abx092064-40tests | Abbexa | 40 tests |
Cow Brucella Antibody Rapid Test Kit |
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| abx092071-40tests | Abbexa | 40 tests |
Goat Brucella Antibody Rapid Test Kit |
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| abx092070-40tests | Abbexa | 40 tests |
Ciprofloxacin (CPFX) Rapid Test Kit |
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| abx092066-50tests | Abbexa | 50 tests |
Pig Parvovirus Antibody Rapid Test Kit |
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| abx092074-50tests | Abbexa | 50 tests |
Procalcitonin rapid test (Colloidal Gold) |
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| abx095264-80Units | Abbexa | 80 Units |
Chlamydia Rapid Test Device (Swab/Urine) |
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| 173-8537306 | Abbott | 20 Tests/Kit |
Aflatoxin Rapid Test Kit (Colloidal gold) |
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| abx092054-50tests | Abbexa | 50 tests |
Dynamiker Monkeypox Virus Ag Rapid Test |
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| DNK-2114-1 | Dynamiker Biotechnology | 20 tests |
Salbutamol Rapid Test Kit (Colloidal gold) |
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| abx092043-50tests | Abbexa | 50 tests |
Quinolones Rapid Test Kit (Colloidal gold) |
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| abx092046-50tests | Abbexa | 50 tests |
Clenbuterol Rapid Test Kit (Colloidal gold) |
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| abx092040-50tests | Abbexa | 50 tests |
Ractopamine Rapid Test Kit (Colloidal gold) |
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| abx092042-50tests | Abbexa | 50 tests |
Zearalenone Rapid Test Kit (Colloidal gold) |
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| abx092051-50tests | Abbexa | 50 tests |
Zearalenone Rapid Test Kit (Colloidal gold) |
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| abx092056-50tests | Abbexa | 50 tests |
Sulfonamides Rapid Test Kit (Colloidal gold) |
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| abx092047-50tests | Abbexa | 50 tests |
Tetracycline Rapid Test Kit (Colloidal gold) |
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| abx092048-50tests | Abbexa | 50 tests |
Fetal Fibronectin rapid test (Colloidal Gold) |
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| abx095261-80Units | Abbexa | 80 Units |
Deoxynivalenol Rapid Test Kit (Colloidal gold) |
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| abx092052-50tests | Abbexa | 50 tests |
Deoxynivalenol Rapid Test Kit (Colloidal gold) |
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| abx092053-50tests | Abbexa | 50 tests |
Chloramphenicol Rapid Test Kit (Colloidal gold) |
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| abx092045-50tests | Abbexa | 50 tests |
Human Echovirus (ECHO) IgM Rapid Test Kit |
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| abx092093-20tests | Abbexa | 20 tests |
Human Toxoplasma (TOX) IgG Rapid Test Kit |
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| abx092098-20tests | Abbexa | 20 tests |
GENLISA™ Human SARS-CoV-2 (Covid-19) Spike Protein Antigen Quantitative ELISA |
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| KBVH015-10 | Krishgen | 12 × 8 wells |
Cattle and Goat Hydatid Antibody Rapid Test Kit |
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| abx092072-40tests | Abbexa | 40 tests |
Aflatoxin B1 Rapid Test Kit (Colloidal gold) |
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| abx092055-50tests | Abbexa | 50 tests |
Aflatoxin B1 Rapid Test Kit (Colloidal gold) |
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| abx092050-50tests | Abbexa | 50 tests |
TruStrip RDT Testosterone Rapid Test cards, 10/pk |
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| 1880-RDT-10 | Alpha Diagnostics | 1 pk |
Avian Influenza H5N1 Virus Antibody Rapid Test Kit |
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| abx092075-40tests | Abbexa | 40 tests |
Human Treponema Pallidum (TP) Antibody Rapid Test Kit |
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| abx092101-20tests | Abbexa | 20 tests |
Malachite Green Rapid Test Kit (Colloidal gold) |
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| abx092041-10tests | Abbexa | 10 tests |
Rabies Virus Antibodies Rapid Test Kit (Colloidal gold) |
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| abx092033-40tests | Abbexa | 40 tests |
Human Rubella Virus (RV) IgG Rapid Test Kit |
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| abx092097-20tests | Abbexa | 20 tests |
Human Rabies Virus (HRV) IgG Rapid Test Kit |
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| abx092100-20tests | Abbexa | 20 tests |
Human Hantavirus (HV) IgM / IgG Rapid Test Kit |
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| abx092094-20tests | Abbexa | 20 tests |
Human Hepatitis A Virus IgG Rapid Test Kit |
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| abx092012-25tests | Abbexa | 25 tests |
Influenza Rapid Test Control Pack (3 X 1.5mL) |
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| KZMC033 | Zeptometrix | 3 X 1.5mL |
Rotavirus Rapid Test Control Pack (2 X 1.5mL) |
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| KZMC036 | Zeptometrix | 2 X 1.5mL |
Human Enterovirus 71 (EV71) IgM Rapid Test Kit |
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| abx092091-20tests | Abbexa | 20 tests |
Adenovirus Rapid Test Control Pack (2 X 1.5mL) |
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| KZMC035 | Zeptometrix | 2 X 1.5mL |
Livingcare Group Covid-19 Day 2 Testing |
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| COV3000 | Scientific Laboratory Supplies | PK200 |
Phenylethanolamine A Rapid Test Kit (Colloidal gold) |
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| abx092044-50tests | Abbexa | 50 tests |
Canine Parvovirus Antibodies Rapid Test Kit (Colloidal gold) |
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| abx092032-40tests | Abbexa | 40 tests |
Furaltadone Metabolite Rapid Test Kit (Colloidal gold) |
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| abx092035-50tests | Abbexa | 50 tests |
Pseudorabies Virus Antibodies Rapid Test Kit (Colloidal gold) |
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| abx092026-50tests | Abbexa | 50 tests |
Furazolidone Metabolite Rapid Test Kit (Colloidal gold) |
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| abx092036-50tests | Abbexa | 50 tests |
Nitrofurazone Metabolite Rapid Test Kit (Colloidal gold) |
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| abx092038-50tests | Abbexa | 50 tests |
Human Helicobacter Pylori (HP) IgG Rapid Test Kit |
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| abx092090-20tests | Abbexa | 20 tests |
GENLISA™ SARS-CoV-2 (Covid-19) Surrogate Virus Neutralization Test (sVNT) ELISA |
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| KBVH400 | Krishgen | 12 × 8 wells |
Human Chlamydia Pneumoniae (CP) IgG Rapid Test Kit |
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| abx092079-20tests | Abbexa | 20 tests |
Human Chlamydia Pneumoniae (CP) IgM Rapid Test Kit |
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| abx092080-20tests | Abbexa | 20 tests |
Human Hepatitis B Virus Surface Antibody Rapid Test Kit |
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| abx092013-25tests | Abbexa | 25 tests |
Peste des Petits Ruminants Virus Antibody Rapid Test Kit |
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| abx092068-50tests | Abbexa | 50 tests |
TruStrip RDT Rat IgG Rapid Test cards, 10/pk |
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| 6420-RDT-10 | Alpha Diagnostics | 1 Pk |
TruStrip RDT Rat IgG Rapid Test cards, 25/pk |
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| 6420-RDT-25 | Alpha Diagnostics | 1 Pk |
TruStrip RDT Pig IgG Rapid Test cards, 10/pk |
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| 9020-RDT-10 | Alpha Diagnostics | 1 Pk |
TruStrip RDT Pig IgG Rapid Test cards, 25/pk |
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| 9020-RDT-25 | Alpha Diagnostics | 1 Pk |
Human Mycoplasma Pneumoniae (MP) IgG Rapid Test Kit |
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| abx092081-20tests | Abbexa | 20 tests |
Human Mycoplasma Pneumoniae (MP) IgM Rapid Test Kit |
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| abx092082-20tests | Abbexa | 20 tests |
TruStrip RDT Goat IgG Rapid Test cards, 10/pk |
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| 7520-RDT-10 | Alpha Diagnostics | 1 Pk |
TruStrip RDT Goat IgG Rapid Test cards, 25/pk |
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| 7520-RDT-25 | Alpha Diagnostics | 1 Pk |
Cardiac Troponin I (cTnI) rapid test (Colloidal Gold) |
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| abx095265-80Units | Abbexa | 80 Units |
Anticyclic citrullinated peptide antibody rapid test (Colloidal Gold) |
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| abx095260-80Units | Abbexa | 80 Units |
TruStrip RDT Human IgG Rapid test cards, 10/pk |
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| 20007-1-RDT | Alpha Diagnostics | 1 Pk |
TruStrip RDT Human IgG Rapid test cards, 25/pk |
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| 20007-1-RDT-25 | Alpha Diagnostics | 1 Pk |
The OraSure InteliSwab Test showed an overall comparable performance using recombinant nucleocapsid protein and different cultured variants with recorded limits of detection ranging between 3.77 × 10 5 and 9.13 × 10 5 RNA copies/mL. Finally, the sensitivity was evaluated using oropharyngeal swabs from Syrian golden hamsters inoculated with the 6 VOCs. Ultimately, the OraSure InteliSwab COVID-19 Rapid Test showed no decrease in sensitivity between the ancestral SARS-CoV-2 strain and any VOCs including Omicron.