key: cord-0816589-nbkqiey9
authors: Chua, Kyra YL; Holmes, Natasha E; Kwong, Jason
title: Prolonged PCR positivity in health care workers with COVID‐19: implications for practice guidelines
date: 2020-10-12
journal: Med J Aust
DOI: 10.5694/mja2.50809
sha: 85d30e9c541855b2ebb53bfe241fad552ad53d4e
doc_id: 816589
cord_uid: nbkqiey9

nan

Since 10 March 2020, there have been 11 health care workers managed at our hospital diagnosed with mild COVID-19 not requiring hospitalisation, with repeated specimens tested by PCR (Box). All patients with COVID-19 assessed and managed at the Austin Hospital were prospectively included in a clinical database approved by the Austin Health Human Research Ethics Committee (database reference number: CD 20002). The median time from PCR positivity to the second negative swab was 32.5 days (range, 11-53 days). None of these health care workers received any specific antiviral or immunomodulatory treatment.

Our current understanding of the viral kinetics in COVID-19 is incomplete. Pharyngeal viral shedding is very high early in the course of illness 3 and may be prolonged. 4 However, nucleic acid detection cannot differentiate between infectious and non-infectious virus. In a study of nine patients with mild COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was not recoverable by culture after day 8 of illness despite high viral loads by PCR. 3 In another contact tracing study, there were no secondary cases in the group that was exposed after 6 days. 5 These findings suggest that infectivity and transmissibility is low after the initial illness.

In Australia, although there was allowance for the return to work of health care workers with prolonged PCR positivity, this was predicated on rounds of testing in what was assumed to be a "small proportion of people". 1,2 Culture for viable virus is not readily available. The findings in our cohort indicate that persistent positivity is the norm and is in line with international studies. 4 Current guidelines for health care workers' return to work appear conservative, with significant workforce implications if outbreaks were to occur in health care settings. Further studies are urgently required to determine the infectivity in patients with prolonged SARS-CoV-2 viral shedding to find a balance in policy that benefits health care workers, hospitals and patients.

Austin Health, Melbourne, VIC.

Acknowledgements: We thank Jason Trubiano, Head of COVID Unit at Austin Health, for critical review of the manuscript. Unable to ascertain 2 23 na = not applicable; PCR = polymerase chain reaction. * Of two consecutive negative swabs. † Patient with asthma. ‡ The last collected specimen from patient 5 was PCR positive 11 days after initial positive specimen. The nucleic acid detection assay used was the AusDiagnostics Coronavirus Typing (8-well) assay. This is a multiplex-tandem PCR assay that employs two rounds of amplification. The cycle take-off value for the last positive specimen on patient 5 was 23 cycles in the second round of amplification. § Patient with hypertension. ¶ Patient with rheumatoid arthritis. ◆

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