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Study Assesses Timing of Positive COVID-19 Testing and Skin Findings

A recent analysis of data from an international registry on cutaneous manifestations of COVID-19 found polymerase chain reaction (PCR) tests for SARS-2-CoV performed early in the disease course were more likely to be positive, even when the date of onset was defined by skin rather than systemic symptoms.

In the study, researchers analyzed a subgroup of patients entered in the registry that had dermatologic manifestations and information on the timing of PCR and/or antibody testing (n=163).

Among patients with suspected COVID-19 and any cutaneous manifestation, the researchers found PCR positivity occurred a median of 6 days after dermatologic symptoms started, while PCR negativity occurred a median of 14 days later.

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They also found PCR positivity was noted 8 days after symptoms among patients with pernio/chilblains, but negativity was reported a median 14 days later. For all dermatologic manifestations, antibody testing was positive a median 30 days after symptom onset and was positive after a median 27 days for chilblains/pernio.

“More population-level testing data are needed to fully understand the expected timing between disease symptoms and test positivity/negativity,” the researchers concluded. “Positive identification of COVID-19 in minimally-symptomatic patients, including patients with skin findings, remains critical to the public health effort.”


Freeman EE, McMahon DE, Hruza GJ, et al. Timing of PCR and antibody testing in patients with COVID-19 associated dermatologic manifestations. J Am Acad Dermatol. Published online September 10, 2020. doi:10.1016/j.jaad.2020.09.007

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