Determining the Infectivity of SARS-CoV-2

Among 90 patients with positive RT-PCR tests, cycle thresholds >24 and time from symptom onset >8 days were associated with very low rates of culture positivity.

The diagnosis of COVID-19 has depended on reverse transcription polymerase chain reaction (RT-PCR) tests directed at SARS-CoV-2 in samples from the nasopharynx or respiratory sites. However, results may be persistently positive while not indicating infectivity. Virologic culture, although labor intensive and necessitating biological containment, is likely to be a more informative surrogate of viral infectiousness. A recent study of nine patients in Germany indicated that no viable virus was found beyond 8 days from symptom onset (NEJM JW Infect Dis Jun 2020 and Nature 2020 Apr 1; [e-pub]). To further explore the relation between RT-PCR assay findings and infectivity in culture, Canadian researchers used specimens from 90 subjects positive f…

Reviewing Author

Neil M. Ampel, MD

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Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Neil M. Ampel, MD

Disclosures

Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Determining the Infectivity of SARS-CoV-2

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Reviewing Author