UCSF

Problem

The utility of the polymerase chain reaction (PCR) cycle threshold (C_t ) values in the management of patients with coronavirus disease 2019 (COVID-19) remains controversial.

Methods

We assessed the correlation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) C_t values in nasopharyngeal swab samples with the oxygen requirements at the time of sample collection. Specimens were tested with the Simplexa PCR platform, which targets the SARS-CoV-2 ORF1ab and S genes.

Results

We identified 23 COVID-19 patients with 49 C_t values available. While C_t values from ORF1ab and S genes were highly correlated for a given specimen, there was no correlation between C_t values for any of these target genes and the oxygen requirements of the patient at the time of sample collection. We found no differences in the initial nor the nadir C_t values between survivors and non-survivors or mild/moderate versus severe/critical illness at the maximum point of illness.

Conclusion

SARS-CoV-2 C_t values have limited value in the management of COVID-19.