RapCov™ Rapid COVID-19 Test
The RapCov™test results can be useful for the presumptive differentiation between recent and past infection. Results from antibody testing should not be used as the sole basis to diagnose or exclude COVID-19 virus infection or to inform infection status. Positive results are presumptive and must be confirmed by viral nucleic acid detection by RT-PCR for confirmation of COVID-19 virus infection. Positive results may be due to past or present infection with non-COVID-19 virus strains, such as coronavirus HKU1, NL63, OC43, or 229E. Negative results do not rule out COVID-19 infection, particularly in those who have been in contact with the virus. Follow-up testing with a molecular diagnostic should be considered to rule out infection in these individuals.
Disclaimer: This test has not been reviewed by the FDA. FDA review for Emergency Use Authorization (EUA) for the RapCov Rapid COVID-19 Test is in progress. EUA # PEUA200048.
The virus named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), also known as “the COVID-19 virus”, causes the Coronavirus Disease (COVID-19). There has been an outbreak of respiratory disease caused by a COVID-19 virus that was first detected in China and which has now been detected in several locations internationally, including in the United States. Reported illnesses have ranged from very mild (including some with no reported symptoms) to severe, including illness resulting in death. While information so far suggests that most COVID-19 illness is mild, reports out of China suggests serious illness occurs in 16% of cases.
In the first week after the onset of symptoms and viremia, IgM antibodies appear in the blood as the initial immune response to the primary COVID-19 virus infection. These IgM antibodies become undetectable subsequently, therefore, the presence of IgM antibodies suggests a recent COVID-19 infection. IgG antibodies appear in the blood after the first week of the disease and IgG antibody titers remain elevated as immunological memory, therefore, the presence of IgG antibodies suggest a non-recent (past) COVID-19 virus infection. The detection of IgM and IgG antibodies in blood can be useful for the presumptive differentiation between recent and past infection.
When present in the patient sample, COVID-19 specific IgM or IgG antibodies bind to anti-human IgM or IgG antibodies immobilized in two lines across the RapCov cassette membrane. Colloidal gold complexes containing recombinant COVID-19 nucleocapsid antigens are captured by the patient’s IgM or IgG antibodies to give visible pink line(s). A procedural control is included to indicate that the assay has been performed correctly and is valid. The RapCov test does not produce an actual test report. The testing laboratory or health care workers at point-of-care must include the test result information in their report.
Interpretation of Results
PERFORMANCE EVALUATION DATA
A study was performed using blood from two groups of subjects. In group 1 (Healthy subjects; n=18), blood was from subjects not exposed to COVID-19 virus. In group 2 (COVID-19 infection; n=18) blood was positive for COVID-19 infection by RT-PCR. Samples were tested as per manufacturer instructions using the RapCov COVID-19 test. Predictive analytics revealed sensitivity of 89%, specificity of 100%, positive predictive value of 100% and negative predictive values for 90%. The test accuracy as 94.4%. A receiver operating characteristic (ROC) curve was plotted using sensitivity versus 1 − specificity of the Rapid COVID-19 test. For the data obtained from RapCov COVID-19 test, the Area under the ROC curve (AUC) was 0.94 with a p value <0.000, indicating that this test has outstanding discriminating ability. This suggests a 94% chance that the clinician performing the test will correctly distinguish a normal subject from a COVID-19 infected patient based on the presence or absence of IgG/IgM bands. The RapCov COVID-19 test detects the presence of antibodies to COVID-19 with high accuracy, sensitivity and specificity in patients who has RT-PCR proven COVID-19 infection.
Specific Public Health and Medical Uses of Rapcov™ Test
There exists a great need for laboratory assays that measure antibody responses. While serological assays are not well suited to detect acute infections, they support a number of highly relevant public health and medical applications.
- From a community perspective to limit the spread of infection, the Rapcov™ test may help in the following practical ways:
- Presence of IgM antibodies on Rapcov™ test may suggest a recent infection and such a result will support advice of social distancing in order to limit the spread of virus, and an immediate referral for molecular testing (Nasopharyngeal swab RT-PCR to detect viral nucleic acid) to confirm COVID-19 virus infection.
- Presence of IgG antibodies on Rapcov™ test may suggest a non-recent (past) infection as neutralizing antibodies against the COVID-19 virus may be present in the blood. This is a good result. Presence of COVID-19 virus neutralizing IgG antibodies will suggest that the individual is of little concern from a public health perspective and is perhaps unlikely to get infected with COVID-19 virus. Presence of IgG antibodies on Rapcov™ test will also permit to determine who is immune and who is not. This would be very useful for deploying immune healthcare workers in a strategic manner as to limit the risk of exposure and spread of the virus inadvertently.
- In cases where nucleic acid amplification assays (RT-PCR) are negative and there is a strong epidemiological link to COVID-19 infection, serology tests (in the acute and convalescent phase) may support diagnosis of COVID-19 disease.
- Serosurveys are needed to determine the precise rate of infection in an affected area, which is an essential variable to accurately determine the infection fatality rate. Serological surveys can aid investigation of an ongoing outbreak and retrospective assessment of the attack rate or extent of an outbreak.
- From a medical decision-making perspective the information regarding presence of IgG or IgM antibodies in the blood may help save lives in the following ways:
- It may help medical decision making in the treatment of acutely ill hospitalized patients who have CT scan and other clinical findings consistent with COVID-19 disease, but a negative RT-PCR result. In these patients Rapcov™ test may provide information regarding presence of IgG or IgM antibodies to support a diagnosis of COVID-19 infection and facilitate appropriate medical treatments. There is no single ‘Gold Standard’ for the diagnosis of COVID-19 infection. The different diagnostic methodologies provide different information regarding COVID-19 infection and a complete clinical picture is made possible by using information provided by all testing methodologies.
- Currently there are no specific anti-viral treatments for COVID-19 disease. The Rapcov™ test administered in the communities can identify individuals who mounted strong IgG antibody responses and who could serve as donors for the generation of convalescent serum therapeutics. This serum can be administered for prophylaxis and treatment of COVID-19 infection to save lives.