RapCov Clinical Studies
The evaluation of RapCov™ test kits was performed in the US by an independent laboratory (LabCorp; Burlington NC) using serum specimen sourced within US from LabCorp and CantorBioconnect (Santee, CA). ADVAITE performed data analysis in collaboration with LabCorp.
Methods: Serum samples patients who had COVID-19 disease confirmed with molecular analysis (RT-PCR positive) of nasopharyngeal swab, were obtained from two sources (total n = 38) located within the US: (i) Cantor BioConnect, (Santee, CA) (n=15); and (ii) Laboratory Corporation of America (LabCorp) (n=23). Patient demographic details were available for serum obtained from Cantor Bioconnect (n=15). Serum samples had ELISA performed for IgG and IgM antibodies and samples with presence of IgG and/or IgM antibodies were evaluated with RapCov™ test kits. ELISA validation was performed at LabCorp according to CAP/CLIA LDT standards. Borderline or Equivocal ELISA values were treated as positive for presence of antibodies. Control serum samples (n=58) were obtained from a blood draw before March 2019, therefore unlikely to have COVID19 as it had not emerged in the US at that time. Control serum samples were provided by LabCorp. The evaluation was performed over the period March 30, 2020 to April 8, 2020.
ADVAITE shipped the RapCov™ test kits to LabCorb to be tested for evaluation. Serum samples were tested per the manufacturer’s Instruction for Use (IFU) in the order they were received– randomization was not done. Briefly, 10µl of serum was used per specimen and the result readout was 15 minutes after applying the buffer to the sample well. The data was abstracted in an excel file and transmitted to ADVAITE for analysis.
Results: Demographic data was available in 15 serum samples that were obtained from Cantor Bioconnect. Median age was 46 years, M:F ratio was 1:1.1. Median number of days from onset of symptoms to date of blood draw was 17 days. Median number of days from onset of symptoms to date of nasopharyngeal swab collection was 5 days.
For positive RapCov™ test, defined as presence of an IgG band and/or an IgM band, the Positive Percent Agreement (PPA) was 97% with RT-PCR positive COVID-19 virus infection and the Negative Percent Agreement (NPA) was 98%.
For the presence of an IgG band on the RapCov™ test, the Positive Percent Agreement (PPA) was 95% with RT-PCR positive COVID-19 virus infection and the Negative Percent Agreement (NPA) was 100%. For the presence of an IgM band on the RapCov™ test, the Positive Percent Agreement (PPA) was 39% with RT-PCR positive COVID-19 virus infection and the Negative Percent Agreement (NPA) was 98%. The low value of PPA for IgM is likely because the median time of blood draw was 17 days, by which time IgM levels may have reduced to levels that are undetectable with RapCov™ test. Had the median blood draw time been at one week or so after onset of symptoms, IgM PPA would have been higher because IgM appears in blood at about one week after onset of symptoms.
A. Other high priority pathogens from the same genetic family: LabCorp performed a cross-reactivity study using human serum specimen who had Human coronavirus OC43 infection. 14 serum samples were tested on the RapCov™ COVID-19 Rapid Test device according to ADVAITE Instructions for Use. Thirteen (93%) samples tested negative for IgG and one (7%) tested positive for IgG. All samples (100%) tested negative for IgM.
We were unable to test for other non-COVID-19 coronavirus strains, such as coronavirus HKU1, NL63 or 229E because of non-availability of serum.
B. High priority organisms likely in the circulating area:
STUDY 1: LabCorp performed an evaluation of 58 serum specimen that were sourced from within US prior to the SARS-CoV-2. It is likely that most of these individuals had vaccinations and experienced infections with human coronaviruses, therefore the serum should have antibodies. All (100%) samples tested negative for IgG. Fifty-seven samples (98.3%) tested negative and one (1.7%) tested positive for IgM.
STUDY 2: Serum samples of patients who had high priority organisms were obtained from Discovery Life Sciences (Los Osos, CA). Following diagnostic remnant serum samples were obtained:
- Influenza A (n=5 serum specimen). All 5 serum specimen had tested positive with Alere BinaxNOW Influenza A&B card.
- anti-HBV (n=5 serum specimen) All 5 serum specimen had tested positive with Aptima HBV Quant Assay.
- anti-HCV (n=5 serum specimen). All 5 serum specimen had tested positive with Roche COBAS AmpliScreen HCV.
- Antinuclear antibodies (ANA) (n=5 serum specimen). All 5 serum specimen had tested positive with BioRad BioPlex | Multiplexed Microparticle Immunoassay.
- Haemophilus Influenzae (n=5 serum specimen). All 5 serum specimen had tested positive with whole blood culture.
Discovery Life Sciences shipped the serum specimen to Frontage Labs (Exton, PA), an independent a contract research organization (CRO). Frontage labs performed the crossreactivity experiments. The study was performed over the period April 13, 2020 to April 17, 2020.The RapCov tests were performed according manufacturer’s instructions at Frontage Labs.
Results: A pink line was present in the Control area of all test devices, therefore all test results were valid. Serum specimen from all tested high priority organisms (Influenza A, anti-HBV, anti-HCV, ANA and Haemophilus Influenzae) was negative (i.e., Pink bands were absent in the IgG area or IgM area in all of the tested serum specimen). Thus, no crossreactivity was observed with the tested serum specimen.
Class Specificity Studies
In the clinical study performed by LabCorp, there were 16 serum samples that showed presence of IgG antibodies but absence of IgM antibodies by ELISA testing. When tested on RapCov™ COVID-19 Rapid Test device, fifteen (94%) of these serum specimen that have been confirmed to have only IgG (not IgM) by ELISA testing, showed presence of IgG band only. If there were cross reactivity of IgG with the IgM line, then significantly greater number of samples would have shown an IgM line on the RapCov™ test.
We were unable to source serum samples within the first week of onset of symptoms, as at that time only IgM is likely to be positive (not IgG), therefore unable to definitively know whether IgM may cross-react with IgG line. However our current data had one serum specimen that had IgM antibody presence on ELISA testing but not IgG. The RapCov™ test also showed only IgM line (IgG line was absent).