SARS-CoV-2 in the sweat of COVID-19-positive patients: a possible route of transmission?

Non-invasive SARS-CoV-2 RNA detection and human transcriptome analysis using skin surface lipids

There have been several reports of skin manifestations in patients with coronavirus disease 2019 (COVID-19). However, it is unclear whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA can be detected on the skin surface, including the sebum, of these patients. In this study, SARS-CoV-2 RNA was detected using real-time reverse-transcription polymerase chain reaction (RT-PCR) assay of skin surface lipids (SSLs) collected using an oil-blotting film from the faces of hospitalized patients with COVID-19. Human transcriptome analysis was also performed using the same samples. In facial SSLs of patients with COVID-19, the RT-PCR positivity rate was 84.6% (11/13 samples) within 5 days and 30.4% (7/23 samples) by 6-10 days of symptom onset. In the transcriptome analysis, the most characteristic SSL-RNA profile was the upregulation of interferon-stimulated gene (ISG)-related genes, such as ISG15, IFITM1, and MX1. This study presents an alternative technique using SSLs for non-invasive SARS-CoV-2 RNA detection and simultaneous analysis of human molecular pathogenesis in patients with COVID-19.

SARS-CoV-2 Detection by Digital Polymerase Chain Reaction and Immunohistochemistry in Skin Biopsies from 52 Patients with Different COVID-19-Associated Cutaneous Phenotypes

BACKGROUND

COronaVIrus Disease 19 (COVID-19) is associated with a wide spectrum of skin manifestations, but SARS-CoV-2 RNA in lesional skin has been demonstrated only in few cases.

OBJECTIVE

The objective of this study was to demonstrate SARS-CoV-2 presence in skin samples from patients with different COVID-19-related cutaneous phenotypes.

METHODS

Demographic and clinical data from 52 patients with COVID-19-associated cutaneous manifestations were collected. Immunohistochemistry and digital PCR (dPCR) were performed in all skin samples. RNA in situ hybridization (ISH) was used to confirm the presence of SARS-CoV-2 RNA.

RESULTS

Twenty out of 52 (38%) patients presented SARS-CoV-2 positivity in the skin. Among these, 10/52 (19%) patients tested positive for spike protein on immunohistochemistry, five of whom had also positive testing on dPCR. Of the latter, one tested positive both for ISH and ACE-2 on immunohistochemistry while another one tested positive for nucleocapsid protein. Twelve patients showed positivity only for nucleocapsid protein on immunohistochemistry.

CONCLUSIONS

SARS-CoV-2 was detected only in 38% of patients, without any association with a specific cutaneous phenotype, suggesting that the pathophysiology of cutaneous lesions mostly depends on the activation of the immune system. The combination of spike and nucleocapsid immunohistochemistry has higher diagnostic yield than dPCR. Skin persistence of SARS-CoV-2 may depend on timing of skin lesions, viral load, and immune response.