There are three types of neutralization tests:
1. Virus neutralization tests (VNT). This test uses SARS-CoV-2 or recombinant SARS-CoV-2 reporter proteins that may take up to 5 days to complete. Currently, there are no authorized EUA tests.
2. Pseudovirus neutralization tests (pVNT). This test uses recombinant pseudovirus that incorporates the S protein of SARS-CoV-2 and can be performed in a Biosafety Level-2 laboratory. Currently, there are no authorized EUA tests.
3. Competitive neutralization test (cVNT). This test uses binding antibody tests designed to qualitatively detect potentially neutralizing antibodies. The test mimics the interaction of the RBD with the ACE-2 receptor in an ELISA format (similar to the RBD on a virus particle binding to a cell surface ACE-2 receptor). Because this method does not require a viable virus, it can be performed in a BSL-2 laboratory. One testing method of this type has been authorized under an EUA by the FDA.
27. Riepler, Lydia, et al. “Comparison of Four SARS-CoV-2 Neutralization Assays.” Vaccines vol. 9,1 13. 28 Dec. 2020, doi:10.3390/vaccines9010013.28. Zhang V, Jones J, Lynch K: Serum COVID-19 Antibodies: Should We Do Testing for Clinical Diagnostics and Monitoring of Vaccine Efficacy? 2022 AACC Annual Scientific Meeting & Clinical Lab Expo, Chicago, IL, July 25, 2022.
