← Product Code [QYT](/submissions/MI/subpart-d%E2%80%94serological-reagents/QYT) · K240728 # CorDx Tyfast COVID-19 Ag Rapid Test; CorDx COVID-19 Ag Test (K240728) _CorDx, Inc. · QYT · Jun 21, 2024 · Microbiology · SESE_ **Canonical URL:** https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/QYT/K240728 ## Device Facts - **Applicant:** CorDx, Inc. - **Product Code:** [QYT](/submissions/MI/subpart-d%E2%80%94serological-reagents/QYT.md) - **Decision Date:** Jun 21, 2024 - **Decision:** SESE - **Submission Type:** Traditional - **Regulation:** 21 CFR 866.3984 - **Device Class:** Class 2 - **Review Panel:** Microbiology - **Attributes:** Pediatric ## Indications for Use The CorDx Tyfast COVID-19 Ag Rapid Test is a visually read lateral flow immunoassay device intended for the rapid, qualitative detection of SARS-CoV-2 virus nucleocapsid protein antigen directly in anterior nasal swab specimens from individuals with signs and symptoms of COVID-19. This test is for non-prescription home use by individuals aged 14 years or older testing themselves, or adults testing individuals aged 2 years or older. The CorDx Tyfast COVID-19 Ag Rapid Test does not differentiate between SARS-CoV and SARS-CoV-2. All negative results are presumptive. Symptomatic individuals with an initial negative test result must be re-tested once between 48 and 72 hours after the first test using an antigen test or a molecular test for SARS-CoV-2. Negative results do not preclude SARS-CoV-2 infections or other pathogens and should not be used as the sole basis for treatment. Positive results do not rule out co-infection with other respiratory pathogens. This test is not a substitute for visits to a healthcare provider or appropriate follow-up and should not be used to determine any treatments without provider supervision. Individuals who test negative and experience continued or worsening COVID-19 like symptoms, such as fever, cough and/or shortness of breath, should seek follow up care from their healthcare provider. The performance characteristics for SARS-CoV-2 were established from September, 2023, to December, 2023, when SARS-CoV-2 Omicron was dominant. Test accuracy may change as new SARS-CoV-2 viruses emerge. Additional testing with a lab-based molecular test (e.g., PCR) should be considered in situations where a new virus or variant is suspected. ## Device Story Lateral flow immunoassay for qualitative detection of SARS-CoV-2 nucleocapsid protein antigen; utilizes anterior nasal swab specimens. Test strip in plastic cassette contains colloidal-gold conjugated monoclonal antibodies; sample extract migrates along membrane; viral antigen captured by specific monoclonal antibody at test line (T). Procedural control line (C) confirms proper wicking. Visually read by user in home setting; results available in 10 minutes. Negative results are presumptive; serial testing recommended for symptomatic individuals to improve sensitivity. Assists in identifying potential COVID-19 infection; guides users to seek professional medical follow-up if symptoms persist or worsen. ## Clinical Evidence Prospective clinical study of 740 symptomatic subjects (0-7 days post-symptom onset). Compared to 510(k)-cleared RT-PCR. Performance in 693 subjects (0-5 DPSO): PPA 85.6% (95% CI: 78.1-90.8%), NPA 99.5% (95% CI: 98.5-99.8%). Analytical studies included LoD (1x10^4 TCID50/ml), inclusivity testing against variants (Alpha, Gamma, Beta, Delta, Omicron), and interference/cross-reactivity panels. ## Technological Characteristics Lateral flow immunochromatographic membrane assay. Components: sample pad, reagent pad (colloidal-gold conjugated monoclonal antibody), reaction membrane (secondary antibody), absorbing pad. Plastic cassette housing. No electronic components. Sterilization via ethylene oxide (ISO 11135, ISO 10993-7). ## Regulatory Identification For the rapid, qualitative detection of SARS-CoV-2 virus nucleocapsid protein antigen in individuals 2 years and older. ## Predicate Devices - Flowflex COVID-19 Antigen Home Test ([K230828](/device/K230828.md)) ## Submission Summary (Full Text) > This content was OCRed from public FDA records by [Innolitics](https://innolitics.com). If you use, quote, summarize, crawl, or train on this content, cite Innolitics at https://innolitics.com. > > Innolitics is a medical-device software consultancy. We help companies design, build, and clear FDA-regulated software and AI/ML devices, including [a 510(k)](https://innolitics.com/services/510ks/), [a De Novo](https://innolitics.com/services/regulatory/), [a SaMD](https://innolitics.com/services/end-to-end-samd/), [an AI/ML medical device](https://innolitics.com/services/medical-imaging-ai-development/), or [an FDA regulatory strategy](https://innolitics.com/services/regulatory/). {0} FDA U.S. FOOD & DRUG ADMINISTRATION # 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY ## I. Background Information: A 510(k) Number K240728 B Applicant CorDx, Inc. C Proprietary and Established Names CorDx Tyfast COVID-19 Ag Rapid Test; CorDx COVID-19 Ag Test D Regulatory Information | Product Code(s) | Classification | Regulation Section | Panel | | --- | --- | --- | --- | | QYT | Class II | 21 CFR 866.3984 - | MI - Microbiology | ## II. Submission/Device Overview: A Purpose for Submission: To obtain a 510(k) clearance for the CorDx Tyfast COVID-19 Ag Rapid Test. B Measurand: Nucleocapsid protein antigen from SARS-Coronavirus 2 (SARS-CoV-2). C Type of Test: Qualitative lateral flow immunoassay. Food and Drug Administration 10903 New Hampshire Avenue Silver Spring, MD 20993-0002 www.fda.gov {1} III. Intended Use/Indications for Use: A Intended Use(s): The CorDx Tyfast COVID-19 Ag Rapid Test is a visually read lateral flow immunoassay device intended for the rapid, qualitative detection of SARS-CoV-2 virus nucleocapsid protein antigen directly in anterior nasal swab specimens from individuals with signs and symptoms of COVID-19. This test is for non-prescription home use by individuals aged 14 years or older testing themselves, or adults testing individuals aged 2 years or older. The CorDx Tyfast COVID-19 Ag Rapid Test does not differentiate between SARS-CoV and SARS-CoV-2. All negative results are presumptive. Symptomatic individuals with an initial negative test result must be re-tested once between 48 and 72 hours after the first test using an antigen test or a molecular test for SARS-CoV-2. Negative results do not preclude SARS-CoV-2 infections or other pathogens and should not be used as the sole basis for treatment. Positive results do not rule out co-infection with other respiratory pathogens. This test is not a substitute for visits to a healthcare provider or appropriate follow-up and should not be used to determine any treatments without provider supervision. Individuals who test negative and experience continued or worsening COVID-19 like symptoms, such as fever, cough and/or shortness of breath, should seek follow up care from their healthcare provider. The performance characteristics for SARS-CoV-2 were established from September, 2023, to December, 2023, when SARS-CoV-2 Omicron was dominant. Test accuracy may change as new SARS-CoV-2 viruses emerge. Additional testing with a lab-based molecular test (e.g., PCR) should be considered in situations where a new virus or variant is suspected. B Indication(s) for Use: See Intended Use above C Special Conditions for Use Statement(s): OTC - Over The Counter D Special Instrument Requirements: Not Applicable. K240728 - Page 2 of 16 {2} K240728 - Page 3 of 16 ## IV. Device/System Characteristics: ### A Device Description: The CorDx Tyfast COVID-19 Ag Rapid Test is a manually performed and visually read lateral flow immunoassay device intended for the rapid, qualitative detection of SARS-CoV-2 virus nucleocapsid protein antigen directly in anterior nasal swab specimens from individuals with signs and symptoms of COVID-19 when tested at least twice over three (3) days with at least 48 hours between tests. This test is for non-prescription home use by individuals aged 14 years or older testing themselves, or adults testing individuals aged two (2) years or older. This test does not differentiate between SARS-CoV and SARS-CoV-2. ### B Principle of Operation: The test strip enclosed in a cassette housing is comprised of the following components: sample pad, reagent pad, reaction membrane, and absorbing pad. The reagent pad contains colloidal-gold conjugated with a monoclonal antibody against the nucleocapsid protein of SARS-CoV-2; the reaction membrane contains the secondary antibody for the nucleocapsid protein of SARS-CoV-2. The whole strip is fixed inside a plastic cassette. When the sample extract is added into the sample well, conjugates dried onto the reagent pad are dissolved and migrate along with the sample. If SARS-CoV-2 nucleocapsid antigen is present in the sample, a complex formed between the anti-SARS-2 conjugate and the viral antigen will be captured by the specific anti-SARS-2 monoclonal antibody coated on the test line region (T). Absence of the test line (T) suggests a negative result. To serve as a procedural control, a red line will always appear in the control line region (C) indicating that proper volume of sample has been added and membrane wicking has occurred. The CorDx Tyfast COVID-19 Ag Rapid Test may give three possible outcomes, positive results, negative results, or an invalid test that would require retesting with a new device. ## V. Substantial Equivalence Information: ### A Predicate Device Name(s): Flowflex COVID-19 Antigen Home Test ### B Predicate 510(k) Number(s): K230828 ### C Comparison with Predicate(s): | Device & Predicate Device(s): | K240728 | K230828 | | --- | --- | --- | | Device Trade Name | CorDx Tyfast COVID-19 Ag Rapid Test | Flowflex COVID-19 Antigen Home Test | | General Device Characteristic Similarities | | | | Intended Use/ | | The Flowflex COVID-19 Antigen | {3} K240728 - Page 4 of 16 | Device & Predicate Device(s): | K240728 | K230828 | | --- | --- | --- | | Indications For Use | The CorDx Tyfast COVID- 19 Ag Rapid Test is a visually read lateral flow immunoassay device intended for the rapid, qualitative detection of SARS-CoV-2 virus nucleocapsid protein antigen directly in anterior nasal swab specimens from individuals with signs and symptoms of COVID-19. This test is for non-prescription home use by individuals aged 14 years or older testing themselves, or adults testing individuals aged 2 years or older. The CorDx Tyfast COVID- 19 Ag Rapid Test does not differentiate between SARS-CoV and SARS-CoV-2. All negative results are presumptive. Symptomatic individuals with an initial negative test result must be re-tested once between 48 and 72 hours after the first test using an antigen test or a molecular test for SARS-CoV-2. Negative results do not preclude SARS-CoV-2 infections or other pathogens and should not be used as the sole basis for treatment. Positive results do not rule out co-infection with other respiratory pathogens. This test is not a substitute for visits to a healthcare provider or appropriate follow-up and should not be used to determine any treatments without provider supervision. Individuals who test negative and experience continued or worsening COVID-19 like symptoms, such as fever, cough and/or shortness of breath, should seek follow up care from their healthcare provider. The performance characteristics for SARS-CoV-2 were established from September, 2023, to December, 2024, when SARS-CoV-2 Omicron was dominant. Test accuracy may change as new SARS-CoV-2 viruses | Home Test is a visually read lateral flow immunoassay device intended for the rapid, qualitative detection of SARS-CoV-2 virus nucleocapsid protein antigen directly in anterior nasal swab specimens from individuals with signs and symptoms of COVID-19 within the first 6 days of symptom onset. This test is for non-prescription home use by individuals aged 14 years or older testing themselves, or adults testing individuals aged 2 years or older. The Flowflex COVID-19 Antigen Home Test does not differentiate between SARS-CoV and SARS-CoV-2. All negative results are presumptive. Symptomatic individuals with an initial negative test result must be re-tested once between 48 and 72 hours after the first test using either an antigen test or a molecular test for SARS-CoV-2. Negative results do not preclude SARS-CoV-2 infections or other pathogens and should not be used as the sole basis for treatment. Positive results do not rule out co-infection with other respiratory pathogens. This test is not a substitute for visits to a healthcare provider or appropriate follow-up and should not be used to determine any treatments without provider supervision. Individuals who test negative and experience continued or worsening COVID-19 like symptoms, such as fever, cough and/or shortness of breath, should seek follow up care from their healthcare provider. The performance characteristics for SARS- CoV-2 were established from December 2022 to March 2023 when SARS- CoV-2 Omicron was dominant. Test accuracy may change as new SARS- CoV-2 viruses | {4} K240728 - Page 5 of 16 | Device & Predicate Device(s): | K240728 | K230828 | | --- | --- | --- | | | emerge. Additional testing with a lab-based molecular test (e.g., PCR) should be considered in situations where a new virus or variant is suspected. | emerge. Additional testing with a lab-based molecular test (e.g., PCR) should be considered in situations where a new virus or variant is suspected. | | Intended Use Setting | OTC | Same | | Regulation Number | 21 CFR 866.3984 | Same | | Classification Regulation | Class II | Same | | Product Code | QYT | Same | | Organism Detected | SARS-CoV-2 | Same | | Analyte | Nucleocapsid protein antigen from SARS-CoV-2 | Same | | Principle of the Technology | Qualitative lateral flow immunoassay | Same | | Sample Type | Anterior nasal swab specimens | Same | | Detection Format | Test cassette, visually read without an instrument. | Same | | Assay Result | Qualitative (positive, negative, invalid) | Same | | Reagent Storage | Store at 36~86°F/2~30°C | Same | | Method to Obtain Result | Visually read by user | Same | | General Device Characteristic Differences | | | | Development Time | 10 minutes | 15 minutes | The differences in the CorDx Tyfast COVID-19 Ag Rapid Test (the candidate device) and the ACON Flowflex COVID-19 Antigen Home Test (the predicate device, K230828) are limited and the biggest difference is the development time. These differences do not affect the overall substantial equivalence of the proposed device to the predicate device in terms of the technological similarity, intended use, safety and effectiveness. VI. Standards/Guidance Documents Referenced: | Document Title | Issued by | Applicable study | | --- | --- | --- | | Reclassification order for DEN220028 and special controls under 21 CFR 866.3984 for Over- the-counter tests to detect SARS-CoV-2 from clinical specimens | FDA/CDRH | All Studies | | ISO11135:2014, Sterilization of health care products - Ethylene oxide - Requirements for development, validation and routine control of a sterilization process for medical devices | ISO | Sterility | | ISO 10993-7, Biological Evaluation of Medical Devices – Part 7: Ethylene Oxide Sterilization Residuals | ISO | Sterility | {5} K240728 - Page 6 of 16 | Document Title | Issued by | Applicable study | | --- | --- | --- | | ISO 10993-1, Biological Evaluation of Medical Devices – Part 1: Evaluation and testing within a risk management process | ISO | Biocompatibility | | EP5-A3 Evaluation of Precision of Quantitative Measurement Procedures | CLSI | Precision | | EP12-A2 User Protocol for Evaluation of Qualitative Test Performance | CLSI | Precision | | EP25A Evaluation of Stability of In Vitro Diagnostic Reagents | CLSI | Reagent stability | | EP37 Supplemental Tables for Interference Testing in Clinical Chemistry | CLSI | Interference | ## VII. Performance Characteristics: ### A Analytical Performance: #### 1. Multi-lot Precision: A precision study was conducted to assess variability with respect to days, operators, and device lots. The study included three device lots, each tested by two operators in triplicates for each sample concentration. The study was conducted over 10 consecutive days (i.e., 3 lots x 2 operators x 3 replicates x 10 days = 180 measurements/sample). Samples with three concentrations of heat inactivated SARS-CoV-2 virus material (Isolate: USA-WA1/2020) were generated by spiking the virus material into negative nasal wash matrix (NWM) as follows: 1. Negative Sample 2. Low Positive Sample at 2xLoD 3. Positive Sample at 4xLoD 50μL of each sample was applied to dry nasal swabs. After blinding and randomizing, samples were processed per the IFU of the candidate device. All results were concordant with the expected results for the virus concentrations of the samples (Table 1), and no variability was observed across the conditions, operators, lots, and days. Table 1. Precision Study Summary Results. | Lot | Negative | | Low Positive (2xLoD) | | Positive (4xLoD) | | | --- | --- | --- | --- | --- | --- | --- | | | Operator 1 | Operator 2 | Operator 1 | Operator 2 | Operator 1 | Operator 2 | | 230201 | 0/30 | 0/30 | 30/30 | 30/30 | 30/30 | 30/30 | | 230202 | 0/30 | 0/30 | 30/30 | 30/30 | 30/30 | 30/30 | | 230203 | 0/30 | 0/30 | 30/30 | 30/30 | 30/30 | 30/30 | | Total | 0/90 | 0/90 | 90/90 | 90/90 | 90/90 | 90/90 | | Agreement | NPA | NPA | PPA | PPA | PPA | PPA | | % | 100 | 100 | 100 | 100 | 100 | 100 | | 95%CI | 95.91-100 | 95.91-100 | 95.91-100 | 95.91-100 | 95.91-100 | 95.91-100 | {6} # 2. Linearity: Not applicable, the device is a binary qualitative assay that is visually read. # 3. Analytical Specificity/Interference: # a. Cross-Reactivity and Microbial Interference A panel of microorganisms commonly found as either pathogens or normal flora in respiratory samples were individually spiked into a negative clinical nasal wash matrix (NWM). The used matrix was supported by a matrix equivalency study and found to be equivalent to negative clinical nasal swab matrix. The organisms were then evaluated for their ability to cross-react with the antibodies of the test by adding $50\mu \mathrm{l}$ of each sample directly to the test swab and then processing the sample swabs per the test's QRI. The study was performed with three replicates per microorganism. Microbial Interference testing was done in the same manner but in the presence of SARS-CoV-2 (USA-WA1/2020) co-spiked into the samples at 3xLoD. Table 2. Cross-Reactivity and Microbial Interference Testing Results. | Microorganism | Concentration Tested | Cross Reactivity Result | Interference Result | | --- | --- | --- | --- | | Human coronavirus 229E | 1x105TCID50/mL | 0/3 | 3/3 | | Human coronavirus OC43 | 1x105TCID50/mL | 0/3 | 3/3 | | Human coronavirus NL63 | 1x105TCID50/mL | 0/3 | 3/3 | | MERS-coronavirus | 1x105TCID50/mL | 0/3 | 3/3 | | SARS-coronavirus (Gamma-irradiated virus in Vero E6 cells in DMEM) | 1x105PFU/mL | 0/3 | N/A | | SARS-coronavirus (Gamma-irradiated virus in PBS) | 1x107PFU/mL | 0/3 | 3/3 | | Human Adenovirus 1 | 1x106TCID50/mL | 0/3 | 3/3 | | Human Metapneumovirus 3 (hMPV-3) Type B1 | 1x105TCID50/mL | 0/3 | 3/3 | | Parainfluenza virus – Type 1 | 1x107TCID50/mL | 0/3 | 3/3 | | Parainfluenza virus – Type 2 | 1x105TCID50/mL | 0/3 | 3/3 | | Parainfluenza virus – Type 3 | 1x107TCID50/mL | 0/3 | 3/3 | | Parainfluenza virus – Type 4A | 1x105TCID50/mL | 0/3 | 3/3 | | Influenza A/Perth/16/09 (H3N2) | 1x105TCID50/mL | 0/3 | 3/3 | | Influenza A/California/07/09 (H1N1) | 1x105TCID50/mL | 0/3 | 3/3 | | Influenza B/Brisbane/60/08 (Victoria) | For Cross-reactivity: 4.68 x104TCID50/mL For Interference: 2.34 x104TCID50/mL | 0/3 | 3/3 | | Influenza B/Wisconsin/01/10 (Yamagata) | 1x105TCID50/mL | 0/3 | 3/3 | | Enterovirus B111 2015 isolate | 1x106TCID50/mL | 0/3 | 3/3 | | Respiratory syncytial virus | 1x106TCID50/mL | 0/3 | 3/3 | | Rhinovirus Type 1A | 1x105TCID50/mL | 0/3 | 3/3 | | Haemophilus influenzae type b (Eagan) | 1x107CFU/mL | 0/3 | 3/3 | | Streptococcus pneumoniae Z022 | 1x107CFU/mL | 0/3 | 3/3 | | Streptococcus pyogenes Z018 | 1x107CFU/mL | 0/3 | 3/3 | | Candida albicans Z006 | 1x107CFU/mL | 0/3 | 3/3 | K240728 - Page 7 of 16 {7} | Microorganism | Concentration Tested | Cross Reactivity Result | Interference Result | | --- | --- | --- | --- | | Pooled human nasal wash – representative of normal respiratory microbial flora | NA | 0/3 | 3/3 | | Bordetella pertussis A639 | 1x10^{7} CFU/mL | 0/3 | 3/3 | | Mycoplasma pneumoniae M129 | 1x10^{7} CCU/mL | 0/3 | 3/3 | | Chlamydia pneumoniae | 1x10^{7} IFU/mL | 0/3 | 3/3 | | Legionella pneumophila Philadelphia | 1x10^{7} CFU/mL | 0/3 | 3/3 | | Staphylococcus aureus MRSA; COL | 1x10^{7} CFU/mL | 0/3 | 3/3 | | Staphylococcus epidermidis MRSE; PR62A | 1x10^{7} CFU/mL | 0/3 | 3/3 | Neither cross-reactivity nor microbial interference was observed for any of the tested microorganisms at the concentration used in the study. An *in silico* analysis was performed for human coronavirus HKU1, and the lower respiratory pathogens *Mycobacterium tuberculosis* (TB), and Pneumocystis jirovecii to evaluate potential cross-reactivity/interference with these microorganisms in lieu of wet testing. The analysis did not identify significant homology between the SARS-CoV-2 Nucleocapsid protein and *Pneumocystis jirovecii* or *Mycobacterium tuberculosis*. Homology was identified between the Nucleocapsid proteins of SARS-CoV-2 and Human Coronavirus HKU1. The highest homology was 39.1% for one segment within 76% of available sequences, and cross-reactivity/interference cannot be ruled out. ## b. Endogenous / Exogenous Interfering Substances Study Two separate studies to evaluate interference from endogenous and exogenous substances were performed. Both studies had a similar study design using three device lots and triplicate measurements of samples contrived in NWM. Samples were contrived by individually adding the substances listed in Table 3 below and testing with or without virus spiked into the sample. 50 µL of each contrived sample was applied to the head of a swab and processed per the IGU/QRI of the test. No false results were observed (Table 3). Table 3. Endogenous / Exogenous Interfering Substances Summary Data | Potential Interfering Substance | Concentration | Without SARS-CoV-2 | With SARS-CoV-2 | | --- | --- | --- | --- | | No other substance | N/A | 0/6* | 6/6* | | Whole Blood | 4% | 0/3 | 3/3 | | Mucin | 0.5% | 0/3 | 3/3 | | Chloraseptic (Menthol/ Benzocaine) | 3mg/mL | 0/3 | 3/3 | | Chloraseptic (Menthol/Benzocaine) | 1.5 mg/mL | 0/3 | 3/3 | | Naso GEL (NeilMed) | 5% v/v | 0/3 | 3/3 | | CVS Nasal Drops (Phenylephrine) | 15% v/v | 0/3 | 3/3 | | Afrin (Oxymetazoline) | 15% v/v | 0/3 | 3/3 | | CVS Nasal Spray (Cromolyn) | 15% v/v | 0/3 | 3/3 | | Zicam | 5% v/v | 0/3 | 3/3 | | Homeopathic (Alkalol) | 10% v/v | 0/3 | 3/3 | | Sore Throat Phenol Spray | 15% v/v | 0/3 | 3/3 | | Tobramycin | 4 µg/mL | 0/3 | 3/3 | | Mupirocin | 10 mg/mL | 0/3 | 3/3 | | HealthA2Z Fluticasone Propionate Nasal Spray | 15% v/v | 0/3 | 3/3 | | Fluticasone Propionate | 5% v/v | 0/3 | 3/3 | K240728 - Page 8 of 16 {8} | Tamiflu (Oseltamivir Phosphate) | 5 mg/mL | 0/3 | 3/3 | | --- | --- | --- | --- | | Chloraseptic (Menthol/ Benzocaine) | 3mg/mL | 0/3 | 3/3 | | Gericare Saline Nasal Spray (Sodium chloride with preservatives) | 15% v/v | 0/3 | 3/3 | | CVS Health Budesonide Allergy Nasal Spray (Budesonide) | 15% v/v | 0/3 | 3/3 | | Nasonex 24HR Allergy Nasal Spray (Mometasone) | 15% v/v | 0/3 | 3/3 | | Luffeel Nasal Spray (Luffa opperculata, Sulfur) | 1.25% v/v | 0/3 | 3/3 | | Boiron Galphimia glauca | 15% v/v | 0/3 | 3/3 | | Boiron Histaminum Hydrochloricum | 15% v/v | 0/3 | 3/3 | *Conglomerate results from both independent studies. 4. Assay Reportable Range: Not applicable, the device is a binary qualitative assay that is visually read. 5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods): a. Controls Internal Control: The CorDx Tyfast COVID-19 Ag Rapid Test has a built-in internal procedural control. A red line should always appear in the control line region (C) indicating that proper volume of sample has been added and that membrane wicking has occurred. The anti-SARS-CoV-2 antibodies are conjugated with colloid gold nanoparticles leading to the coloration of the C line. External Controls: This test is for OTC distribution. As such the test kits will not contain external controls as lay users are not required to perform external control testing. However, for professional use setting, the CorDx Tyfast COVID-19 Ag Rapid Test External Control Kit can be obtained separately as an accessory to the test. b. Device Stability: Real Time Stability (Shelf life): The stability of the CorDx Tyfast COVID- 19 Ag Rapid Test was determined for the intended storage conditions, 2-30°C (36-86°F), and an intended shelf life of 24 months. Within one month of manufacture three device lots were transferred to five different temperatures (-20°C, 2°C, 15°C, 30°C and 40°C), where they were stored for 27 months. Testing of the kit lots was performed every 3 months with 5 replicates/timepoint, lot and test sample concentration. Two test samples, corresponding to 3.6xLoD and at 4.6xLoD, were tested at each time point. All study data were 100% concordant with expected results and thereby supportive of the 24 months shelf life at 2-30°C (36-86°F). Shipping Stability: The effects of shipping on the integrity of the test device were evaluated with three device lots that were manufactured within one month of study start. These were exposed to either cycles of temperature and humidity fluctuations or mechanical stress. Temperature cycles K240728 - Page 9 of 16 {9} included temperatures from -20 to +55°C with relative humidities between 20 and 90%, depending on the cycle. All results were concordant with expected results supporting stability during the anticipated shipping conditions for the test. ## 6. Detection Limits: ### a. Limit of Detection (LoD): The LoD study was performed in parallel with NWM and NSM to demonstrate the equivalency of both matrices. NWM was used in most of the analytical validation studies. In this study a heat inactivated SARS-CoV-2 virus culture fluid (Isolate: USA-WA1/2020; ZeptoMetrix) was spiked into the negative matrices, and samples were then diluted in 10-fold steps. 50μl of each dilution was added directly to the test swab and the swab samples processed per the QRI. The LoD was assessed with three device lots. For the preliminary LoD study, testing was performed with five replicates per lot. The lowest concentration with >95% detection was then tested with 20 randomized replicates to confirm the LoD (Table 4). The LoD for both matrices was confirmed at 1×10⁴ TCID₅₀/ml with 57/60 (C₉₅) positive results, and both matrices were determined to be equivalent. This LoD was independently confirmed by a second study conducted as part of the ITAP program. Table 4. LoD Study Summary - UV Inactivated SARS-CoV-2 (USA-WA1/2020) | Matrix | Concentration | | Lot: 230201 | | Lot: 230202 | | Lot: 230203 | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | | TCID₅₀/ml | TCID₅₀/Swab | P | C | P | C | P | C | | NWM | 1×10⁷ | 5×10⁵ | 5/5 | N/A | 5/5 | N/A | 5/5 | N/A | | | 1×10⁶ | 5×10⁴ | 5/5 | N/A | 5/5 | N/A | 5/5 | N/A | | | 1×10⁵ | 5×10³ | 5/5 | 20/20 | 5/5 | 20/20 | 5/5 | 20/20 | | | 1×10⁴ | 5×10² | 5/5 | 19/20 | 5/5 | 19/20 | 5/5 | 19/20 | | | 1×10³ | 5×10¹ | 0/5 | 0/20 | 0/5 | 0/20 | 0/5 | 0/20 | | | 1×10² | 5 | 0/5 | N/A | 0/5 | N/A | 0/5 | N/A | | | 1×10¹ | 5×10⁻¹ | 0/5 | N/A | 0/5 | N/A | 0/5 | N/A | | NSM | 1×10⁷ | 5×10⁵ | 5/5 | N/A | 5/5 | N/A | 5/5 | N/A | | | 1×10⁶ | 5×10⁴ | 5/5 | N/A | 5/5 | N/A | 5/5 | N/A | | | 1×10⁵ | 5×10³ | 5/5 | 20/20 | 5/5 | 20/20 | 5/5 | 20/20 | | | 1×10⁴ | 5×10² | 5/5 | 19/20 | 5/5 | 19/20 | 5/5 | 19/20 | | | 1×10³ | 5×10¹ | 0/5 | 0/20 | 0/5 | 0/20 | 0/5 | 0/20 | | | 1×10² | 5 | 0/5 | N/A | 0/5 | N/A | 0/5 | N/A | | | 1×10¹ | 5×10⁻¹ | 0/5 | N/A | 0/5 | N/A | 0/5 | N/A | P: Preliminary Study. C: Confirmatory LoD Study. ### b. NIBSC 21/368 – WHO International Standard The sponsor tested the sensitivity of the test against the 1st WHO International Standard for SARS-CoV-2 antigen (NIBSC code: 21/368) spiked into NSM. The unitage of this material has an assigned value of 5,000 International Units of SARSCoV-2 antigen per ampoule when reconstituted per instructions. A 2-fold dilution series was made to determine the preliminary LoD, which was measured using one device lot and triplicate measurements (n=3). The measurements were done by adding 50μl of each dilution directly to the test swab and processing the sample per the test’s QRI (Table 5). The preliminary LoD was determined to be 5×10² IU/ml. K240728 - Page 10 of 16 {10} The LoD confirmatory study was performed using 20 replicates $(n = 20)$ per dilution (Table 5). The lowest concentration at which a minimum of $95\%$ of results were positive was confirmed to be $5\times 10^{2}$ IU/ml or $2.5\times 10^{1}$ IU/Swab. Table 5. LoD Study Summary – $1^{\text{st}}$ WHO International Standard for SARS-CoV-2 antigen (NIBSC code: 21/368) | Preliminary LoD | | Confirmatory LoD | | | --- | --- | --- | --- | | Dilution (IU/ml) | Results | Dilution (IU/ml) | Results | | 4x103 | 3/3 | N/A | N/A | | 2x103 | 3/3 | N/A | N/A | | 1x103 | 3/3 | 1.5x103 | 20/20 | | 5x102 | 3/3 | 5x102 | 20/20 | | 2.5x102 | 1/3 | 1.67x102 | 8/20 | | 1.25x102 | 0/3 | N/A | N/A | | 6.25x101 | 0/3 | N/A | N/A | | 3.13x101 | 0/3 | N/A | N/A | # 7. Inclusivity An evaluation of the sensitivity of the test for the detection of relevant SARS-CoV-2 variants was done by testing the detection limits of the test with seven heat inactivated virus variant reagents that show diverging mutations in the nucleocapsid protein. Specifically, variants B.1.1.7 (Alpha), P.1 (Gamma), B.1.595 (Gamma), B.1.351 (Beta), B.1.617.2 (Delta), B1.1.529 (Omicron), and XBB (Omicron). The virus reagents were spiked into NSM and serial diluted 2-fold in NSM were performed thereafter. Each dilution was tested with five replicates by adding $50\mu l$ contrived sample directly onto each test swab and processing the swab samples per the test's QRI. The number of positive replicates for the tested variants are shown in Table 6 below with highlight on the lowest concentration that detected $>95\%$ of all replicates. Table 6. LoD of SARS-CoV-2 Variants. | Concentration (TCID50/ml) | B.1.1.7 (Alpha) | P.1 (Gamma) | B.1.595 (Gamma) | B.1.351 (Beta) | B.1.617.2 (Delta) | B1.1.529 (Omicron) | XBB (Omicron) | | --- | --- | --- | --- | --- | --- | --- | --- | | 1x105 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | | 5x104 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | | 2.5x104 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 | | 1.25x104 | 2/5 | 0/5 | 5/5 | 0/5 | 5/5 | 5/5 | 0/5 | | 6.25x103 | 0/5 | 0/5 | 5/5 | 0/5 | 5/5 | 5/5 | 0/5 | | 3.13x103 | 0/5 | 0/5 | 5/5 | 0/5 | 5/5 | 5/5 | 0/5 | | 1.56x103 | 0/5 | 0/5 | 5/5 | 0/5 | 0/5 | 0/5 | 0/5 | | 7.81x102 | 0/5 | 0/5 | 5/5 | 0/5 | 0/5 | 0/5 | 0/5 | | 3.91x102 | 0/5 | 0/5 | 5/5 | 0/5 | 0/5 | 0/5 | 0/5 | | 1.95x102 | 0/5 | 0/5 | 0/5 | 0/5 | 0/5 | 0/5 | 0/5 | Beyond the testing described above, Omicron JN.1.1 was independently evaluated with the test showing detection down to an average Ct of 25.4 (139015.1 GE/ml). As an extension of the inclusivity testing, a deep mutational screen was performed to identify amino acid residues in the SARS-CoV-2 nucleocapsid antigen that are critical for the paratope-epitope affinity for the antibodies used in the test. This knowledge will help identify future and emergent variants that may not be sufficiently detected by the test. K240728 - Page 11 of 16 {11} K240728 - Page 12 of 16 8. High Dose Hook Effect: An assessment of whether a high dose hook effect exists for the test was done using a serial dilution of UV-inactivated SARS-CoV-2 virus (Stock concentration: 4.57×10⁶ TCID₅₀/ml). The virus was spiked into negative NWM, and 50μl of sample was added directly to the head of the swabs. Swabs were processed per the test's IFU/QRI. Testing was done across three device lots. Each of the 3 operators performed a single measurement for each concentration per lot (Table 7). No high dose hook effect was observed in the study, up to the maximum concentration tested herein. Table 7. High Dose Hook Effect Data Summary. | Virus Concentration (TCID_{50}/ml) | xLoD | Results | | --- | --- | --- | | 4.57×10^{6} | 365.6 | 3/3 | | 2.5×10^{6} | 200 | 3/3 | | 1.25×10^{6} | 100 | 3/3 | | 6.25×10^{5} | 50 | 3/3 | | 1.25×10^{5} | 10 | 3/3 | | 2.5×10^{4} | 2 | 3/3 | B Comparison Studies: 1. Method Comparison with Predicate Device: Not applicable. See "C. Clinical Studies" for performance comparison with a clinical comparator. 2. Matrix Comparison: The CorDx COVID-19 Ag Test is only intended for use with direct anterior nasal swab specimens. As no other specimen or sample type is used with this device, a matrix comparison study to support other sample types for clinical testing with this device was not performed. However, as part of the LoD study (see section VII. A. 6.a) the sponsor conducted a matrix equivalency study between pooled negative nasal swab matrix and the surrogate negative clinical nasal wash matrix (NWM) that was used in the analytical studies. The data demonstrated the equivalent performance of the test with both matrices. C Clinical Studies: 1. Clinical Sensitivity and Specificity: A prospective lay person clinical study was conducted to assess the performance of the candidate test in a simulated at-home setting when compared to a highly sensitive 510(k)-cleared SARS-CoV-2 RT-PCR assay with an extraction step. The study enrolled symptomatic subjects at four clinical study sites between September 09, 2023, and December 11, 2023, when Omicron was the most prevalent SARS-CoV-2 strain in the U.S. Both, the comparator and the candidate test, used anterior nasal swab samples, and the collection order was alternated (randomized) by study subject. Comparator test samples were collected by health care professionals at the clinical study site and inserted into Universal Transport Media per the IFU of the comparator test. Samples for the candidate antigen test {12} were collected per the test's QRI and were either self-collected by a lay user aged $\geq 14$ years or collected by an adult (parent/guardian) from individuals aged 2 to $< 14$ years. 751 study subjects were enrolled in total, of which 740 subjects between 0 and 7 days post symptom onset (DPSO) had valid comparator test results and were evaluable per the study protocol. Detailed study subject demographics are listed below (Table 8). Table 8: Demographics - Age Distribution and Education of the Clinical Study Cohort | Age group | Percent total | Total | | --- | --- | --- | | 2-13 years* | 22% | 163 | | 14-21 years | 9.1% | 67 | | 22-64 years | 60.1% | 445 | | ≥65 years | 8.8% | 65 | | | | | | | | | | | | | | | | | | | | | | Total | 100% | 740 | *Tested by adult >14 years old per the intended use statement. **32 users age 14 to <18 did not finish high school yet | Education | Lay user | Total | | --- | --- | --- | |