Case Studies | CardiAI™

Does the Limit of detection play a role in deciding whether the test is positive, or negative Let us say that we have Joe who has recently been exposed to Covid-19.

Joe got himself tested by a normal PCR test on the second day of exposure and got a negative result. So, Joe does not worry about his condition, and he is going on a regular routine. He is going out and working with his colleagues. After 4 days Joe decided to get himself tested with CoviLamp-PCR, the results came positive while the normal PCR test results indicated Joe was negative for Covid-19 infection. negative with the.

To clarify the false positive and false negative results, he was again tested with a normal PCR test on the next day. He became more positive and realized he was spreading the virus to the people he was engaged with.

Scientific explanation: Discrepancy in the test results can be explained using following criteria’s:

Variation in sample
Normal PCR test usually uses oropharyngeal swabs as compared to CoviLamp’s saliva or nasal. Scientific literature indicates that patients from whom saliva was collected tested positive at a significantly higher rate than those where the sample came from NS.
Variation In Sensitivity
CoviLamp limit of detection is between 6.25copies/microliter to 12.5 copies as compared to normal PCR test which has a LOD of approximately 30-40 copies/microliter Our LOD studies have been validated by 3 rd party CLIA certified; FDA recognized lab
Selectivity
CoviLamp uses 6 different primer sets to amplify target genome vs normal PCR test where only 2 primers and a probe is used
Variation In Extraction /Elution Volume
CardiAI elutes sample in much concentrated form –elution volume 25 microliters vs normal PCR test (100 microliters). Thus incorporating high template (target gene; CardiAI) in sample vs diluted template gene (normal PCR test ) in the final reaction. The samples with high template reaches threshold faster than low template samples thus can be considered as negative in various PCR test.