Screening for Antibodies (IgG) to the COVID-19 virus infection
Diagnosing the COVID-19 viral infection relies on two major methodologies: 1) identification of the viral RNA (antigen) using polymerase chain reaction analysis, and 2) serological immunoassays that detect the viral-specific antibody IgG.
Screening for COVID-19 RNA uses nasopharyngeal swabs. It identifies the active virus or proteins associated with the virus. This is called an “antigen” test. As the clinical symptoms resolve, the amount of COVID-19 virus being shed tends to decrease, and RNA antigen tests often become negative.
COVID-19 IgG antibody generally first appears 10 days to two weeks after COVID-19 infection starts – often around the time symptoms of infection, if there were any, improve. This is important because the presence of COVID19 IgG antibody may indicate immunity to future COVID-19 infections.
That is why EnMed MicroAnalytics also is committed to working hard and staying up with the latest COVID-19 antibody literature – and notifying you, as soon as more is known about COVID-19 immunity.
Participating companies, in collaboration with EnMed MicroAnalytics, Inc. (EnMed) may elect to offer COVID-19 antibody screening to its employees and its customers. For employees, it is important to determine if they have been exposed and if they are now immune to future infections. This is especially true for employees that have been furloughed or laid off as they return to work, and will be important information if there are future waves of the virus. For high risk patients in nursing homes, for example, it is important to determine their antibody status with or without active virus or clinical symptoms. Antibody screening in conjunction with the RNA test is important. For customers, screening can be offered in pharmacies or parking lot collection stations to provide reassurance among individuals wanting to know if they are immune and when they can safely go back to work. EnMed will be screening serum or plasma samples collected by venipuncture as well as dried blood spot (DBS) samples collected on filter paper cards following a finger prick. We highly recommend the DBS sample. The advantages of the DBS specimen is the ease of sample collection (individuals can self-sample), ease of shipment (no need to ship on ice or use special handling), and reduced biohazard risk both in transit and in the lab (CDC and the Post Office consider DBS specimens nonregulated, exempt material).
EnMed is a CLIA certified and CAP accredited high complexity lab in Charleston, South Carolina. EnMed will provide the supplies necessary for sample collection and transport. This will include the DBS filter paper collection card, alcohol swabs, lancets, information brochures, submitter and individuals information cards, and prepaid, preaddressed mailing envelopes. Reports will be generated, and results quantified with established cut-offs. Our goal is to have results available to authorized submitters within 24-48 hours from time of receipt. Results will be available electronically by logging onto our web portal or be transmitted by an HL7 interface, if one is established. EnMed is using IgG packets from Diazyme Laboratories. The tests are run on the fully automated DZ-Lite 3000 Plus chemiluminescence analyzer. None of the antibody assays have gone through full FDA evaluation; but Diazyme has followed the FDA’s Emergency Use Notification process as provided for in the FDA’s Policy for Diagnostic Tests for Coronavirus Disease-2019 during the Public Health Emergency, dated March 16, 2020. It has taken the next step and obtained an FDA Registration Number. Using traditional CPT Codes for antibody testing, the reimbursement rate has been ~$50. April 10, 2020, the American Medical Association announced a new CPT Code (86769) for antibody testing for COVID-19. It was established for antibody tests using multiple step methods like the method that we use.