diff --git a/src/payload.ts b/src/payload.ts
index 6288a9c..fbe1d17 100644
--- a/src/payload.ts
+++ b/src/payload.ts
@@ -235,7 +235,17 @@ export class Payload {
                     throw new Error('invalidTestType')
                 }
 
-                const testResult = valueSets.testResults[testResultKey].display;
+                let testResult = valueSets.testResults[testResultKey].display;
+
+                switch (testResult) {
+                    case 'Not detected':
+                        testResult = 'Negative';
+                        break;
+                    case 'Detected':
+                        testResult = 'Positive';
+                        break;
+                }
+
                 const testType = valueSets.testTypes[testTypeKey].display;
 
                 const testTime = testDateTimeString.replace(/.*T/, '').replace('Z', ' ') + 'UTC';