Follow-up COVID-19 PCR result up to day 5 with clinical features predicts positivity for inconclusive results

Introduction

False-positive inconclusive polymerase chain reaction (PCR) results against severe acute respiratory syndrome coronavirus 2 were not low and have potentially harmful effects. We aimed to find parameters to differentiate positive cases from false-positive ones, and suggest an optimal scheme and follow-up period for inconclusive results.

Methods

Cases with inconclusive PCR tests among healthcare personnel from February 2020 to June 2021 were classified as confirmed positive, clinically positive, and clinically negative groups, which were compared. The diagnostic accuracy of follow-up tests and composites of clinical and laboratory data were analyzed.

Results

Symptoms, contact history, and lower cycle threshold of the N gene were more common in the COVID-19 positive group. The scoring schemes combining symptom and contact history with follow-up PCR results had higher sensitivities than the PCR tests only modality. Follow-up tests up to 5 days combined with symptoms and contact history could discriminate between positive and negative cases.

Conclusion

A follow-up PCR test up to day 5 with clinical features might predict positivity and shorten the quarantine period in most healthcare personnel.