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rRT-PCR Ct values and infectivity
We know that some of them were having long or months of positivity and we couldn’t
discharge them. At that point in time, we also looked at the rRT-PCR Ct values and
infectivity. We worked closely with the Infectious Disease (ID) team in Hospital Sungai
Buloh. We looked at those patients with Ct values from 32 to 40 on Vero-E6 cells. Ct values
is a proxy for viral load. We found that samples with Ct values above 34 had no growth in
Vero-E6. This means that there was no risk of infectivity. Therefore, patients with these Ct
values can be discharged. However, we have guidelines on discharge criteria. This is to show
that the patients who were sent home and after two week they came back with positive Ct
values of 38 were actually not infective.