Many RNA assays for SARS-CoV-2 check for multiple gene targets and report out an interpretation. For instance there is an assay that if it finds ORF1 a/b but not the E-gene the reported interpretation is “Presumptive”. Which LOINC should be used in this case?
The best source to get LOINC codes for SARS-CoV-2 tests approved by the FDA is the LIVD file published by the CDC - https://www.cdc.gov/csels/dls/sars-cov-2-livd-codes.html. The LOINC team helps maintain this file and it’s updated each week. Can you please check the file and see if the test kit you are using is included?
We also have more information on choosing LOINC codes on our webpage dedicated to SARS-CoV-2 - https://loinc.org/sars-coronavirus-2/.