Trusted Partner for Comprehensive COVID-19 Testing
Our organization strictly adheres to FDA policies and regulations covering the sale of diagnostic testing supplies and services for COVID-19. While personal protective equipment (PPE) may be purchased without restriction, our FDA EUA authorization indicates that these tests are intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection. Emergency use of this test is limited to authorized laboratories.
Always verify FDA Authorization Status Before Purchasing COVID-19 Testing Supplies. You may verify the current status of our products (and any other manufacturer’s products on the FDA website: FDA Listing for In Vitro Diagnostics EUA’s)
The BioHit Antibody Test Kit is designed to confirm the presence of IgM and IgG antibodies in the blood. This test is authorized by the FDA.
The Antigen Assay Kit is used for detection of SARS-CoV-2 N protein in human serum or plasma.
Our High Complexity CLIA Lab is now offering an RT-PCR Saliva Test to provide comprehensive testing solutions.
Cleanmo’s Flocked Swabs are designed for the collection of nasopharyngeal specimens used in PCR testing.
A Comparison of The BioHit SARS-CoV-2 LFA IgM/IgG Antibody assay and the RT-qPCR and Antigen Assays for Detecting SARS-CoV-2 Virus
There are three common forms of detecting SARS-CoV-2 virus infection in patients. Specifically, real-time PCR (RT-qPCR), Antibody Laminar Flow Immunoassays (LFA) and viral Antigen Assays.
1. RT-qPCR assay
In this assay, viral RNA is acquired via nasal swabs. After RNA extraction, the RNA undergoes reverse transcription to yield complementary DNA (cDNA). Then the cDNA is amplified (i.e. copied) millions of times to derive enough cDNA to analyze. This method requires a sophisticated lab, expensive equipment, and well-trained lab technicians. Its procedure (once RNA is extracted) takes up to four hours to run. However, with sample back logs in some areas, reporting results take a week or longer. Test sensitivity (an association of positive test results with patients who accurately have the disease) is initially good. Up to 30% of these assays may produce false negative results because of early collection/processing of samples and poor adherence of virus to the nasal swabs and/or the techniques (pre-RT-qPCR) utilized (1). The graph to the right shows the forms of testing vs. time since onset of symptoms. Please note that symptom onset occurs on average five days after virus exposure/acquisition. As depicted in the graph, the viral load rapidly diminishes to very low levels by eight to nine days after symptom onset (or 13 to 14 days after the virus infection began).
In fact, because of the resultant lower RT-qPCR (and Antigen Assay) test sensitivity, the FDA recommends that for samples collected after eight days of symptoms, that the additional use of an antibody assay would significantly increase detection test sensitivity (2). The benefits of combined testing were also evident in studies promulgated by Zhao, their colleagues and Xie et al. (3,4). Specifically, Zhao and colleagues showed that for the period of one to seven days post symptom onset (PSO) the results of combined antibody and RT-qPCR assays yielded a combined sensitivity of 78.7% in comparison to a sole RT-qPCR assay sensitivity of 66.7% (3). Furthermore, for the period of eight to 14 days PSO the combined sensitivity was 97 % compared to a sole RT-qPCR sensitivity of 54%. In a similar manner, Xie et al. demonstrated that combined assay detection sensitivity was more than three-fold increased in comparison to the results of a RT-qPCR assay alone (4). Similar improvement in detection accuracy and sensitivity is evident in the results of combining an antibody assay with RT-qPCR as published by Wang (5). Wang demonstrated that PCR positive detection occurred in 89% of COVID-19 patients tested during day 0 to 10 PSO, in 20% of patients tested from day 11 to 20 PSO, and in 8% of patients tested more than 20 days PSO. This decreasing positive response is most likely due to decreasing viral loads with time and concomitant decreasing test sensitivities. When calculating in the results of antibody assays, Wang reported that the total RT-qPCR sensitivity of 92.2% for all periods studied, plus the Antibody assay sensitivity of 95.7% for all periods, yielded a combined sensitivity of 98.6% sensitivity. In a similar manner Guo et al. demonstrated that by combining the results of IgM and RT-qPCR assays, the positive detection rate was significantly increased to 98.6% from 51.9% if one relied on a single RT-qPCR assessment only (6). Thus, the clinical utilization of two different testing assays would significantly improve testing sensitivity and accuracy.
2. BioHit SARS-CoV-2 LFA IgM/IgG Antibody assay
This assay can demonstrate the presence of anti-SARS-CoV-2 IgM and IgG antibodies within 15 minutes. It is a low cost, simple and point-of-care assay that is one of the few authorized after extensive testing by the FDA ( 7 ). In addition, it demonstrates excellent test detection sensitivity and specificity as demonstrated by the FDA, a corroborative study from Yale University and the antibody kit manufacturers (please see table below). The authors of the Yale study contrasted their study results with that of one completed by the University of California at San Francisco (UCSF) in which 10 alternative LFA antibody assays were assessed ( 8 ). The Yale study authors point out that the BioHit test IgM and IgG sensitivities were better than the comparable best performing assays in the UCSF study ( 9 ). IgM detection, as detected by a laminar flow immunoassay (LFA) kit is detectable as early as five days PSO. IgG is detectable shortly after IgM (see above graph). Of note, both IgM and IgG assays have high sensitivities throughout the time period specified for assay use (eight days PSO) for combined testing as per the FDA to improve testing sensitivity and accuracy.
3. Antigen Assays
These tests detect specific viral protein antigens; however, unlike PCR methods, no amplification step is incorporated. Therefore, Antigen tests are very specific for the virus, but are not as sensitive as molecular PCR tests. This means that positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection. With this in mind, negative results from an antigen test may need to be confirmed with a PCR test prior to making treatment decisions or to prevent the possible spread of the virus due to a false negative result. Antigen assays usually provide results within seven days PSO (see above graph) which is a shorter diagnostic time span than RT-qPCR. In addition, as the viral load falls so does viral protein content which contributes to the lower Antigen assay sensitivities over time (see graph above). The Quidel Sofia SARS Antigen FIA is a FDA authorized Antigen Assay kit whose instructions contain the following statement, “Negative results, from patients with symptom onset beyond five days, should be treated as presumptive and confirmation with a molecular assay, if necessary, for patient management, may be performed. Negative results do not rule out COVID-19 and should not be used as the sole basis for treatment or patient management decisions, including infection control decisions. Negative results should be considered in the context of a patient’s recent exposures, history and the presence of clinical signs and symptoms consistent with COVID-19 (11).”
News and Research Updates
BioHit Healthcare's Rapid Antibody Test Granted EUA It’s official. Biohit’s SARS-CoV-2 IgM/IgG antibody test kit has just been authorized by FDA under a EUA (Emergency Use Authorization) for use in...
COVID-19 Testing Provider ResourcesThe American Medical Association (AMA)CLICK BELOW TO VIEW/DOWNLOADUnited HealthcareCLICK BELOW TO VIEW/DOWNLOADCenters for Medicare and Medicaid Services...
Corroboration of the Accuracy of the Biohit SARS-CoV-2 IgM/IgG LFA test kitThe human immune response to a COV/0-19 infection encompasses the host synthesis of anti-SARS-CoV-2 lgM antibodies that are...
Main Mechanism of Antigen into Blood When SARS-CoV-2 invades the lung cells, it will express a large amount of self protein to reassemble the virus particles, causing cell damage and forming...
Beware Fake Covid Tests: How to Tell the Good from the Ugly... As the world struggles to find the best way to deal with Covid-19, experts agree on one thing: the importance of good testing. Knowing...