LabCorp antibody test for Covid from their website:
Can semi-quantitative COVID-19 antibody test be used to track antibody levels overtime?
On May 19, 2021, the FDA issued a safety communication reiterating that “antibody testing should not be used to evaluate a person’s level of immunity or protection from COVID-19 at any time, and especially after the person received a COVID-19 vaccination.”4 Currently authorized SARS-CoV-2 antibody tests, including the SARS-CoV-2 Semi-Quantitative Total Antibody assay (164090), have not been evaluated to assess the level of protection provided by an immune response to COVID-19 vaccination. Additionally, the components of a protective immune response against infection or re-infection with SARS-CoV-2 have not been fully characterized (e.g., antibody, T cell, etc.). Clinical trials and other studies are underway to elucidate the correlates of immunity to SARS-CoV-2.

Effective March 28, 2022 Labcorp expanded the reporting range of results for test number 164090 SARS-CoV-2 Semi-Quantitative Total Antibody, Spike. Results previously reported for this assay were 0.8-2500 U/mL with higher values reported as >2500 U/mL. With the addition of an automated dilution, we are now able to report result 0.8-25000 U/mL with higher values reported as >25000 U/mL. This change does not impact previously reported results; it just increases the numerical values above 2500 U/mL that we are able to report.