This code system http://worldhealthorganization.github.io/smart-ot/Result defines the following codes:

CodeDisplay
0 Negative
1 Positive
2 Inadequate specimen
3 Equivocal (indeterminate)
4 Community Case Search
99 Unknown (result not available)
 <status value="draft"/> <date value="2023-11-07T05:59:29+00:00"/> <publisher value="WHO"/> <contact> <name value="WHO"/> <telecom> <system value="url"/> <value value="http://who.int"/> </telecom> </contact> <description value="Result Code System"/> <jurisdiction> <coding> <system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/> <code value="001"/> </coding> </jurisdiction> <content value="complete"/> <count value="6"/> <concept> <code value="0"/> <display value="Negative"/> </concept> <concept> <code value="1"/> <display value="Positive"/> </concept> <concept> <code value="2"/> <display value="Inadequate specimen"/> </concept> <concept> <code value="3"/> <display value="Equivocal (indeterminate)"/> </concept> <concept> <code value="4"/> <display value="Community Case Search"/> </concept> <concept> <code value="99"/> <display value="Unknown (result not available)"/> </concept> </CodeSystem>