ABSTRACT
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: 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.
ABSTRACT
Longitudinal mapping of antibody-based SARS-CoV-2 immunity is critical for public health control of the pandemic and vaccine development. We performed a longitudinal analysis of the antibody-based immune response in a cohort of 100 COVID-19 individuals who were infected during the first wave of infection in northern Italy. The SARS-CoV-2 humoral response was tested using the COVID-SeroIndex, Kantaro Quantitative SARS-CoV-2 IgG Antibody RUO Kit (R&D Systems, Bio-Techne, Minneapolis, USA) and pseudotype-based neutralizing antibody assay. Using sequential serum samples collected from 100 COVID-19 recovered individuals from northern Italy-mostly with mild disease-at 2 and 10 months after their first positive PCR test, we show that 93% of them seroconverted at 2 months, with a geometric mean (GeoMean) half-maximal neutralization titer (NT50) of 387.9. Among the 35 unvaccinated subjects retested at 10 months, 7 resulted seronegative, with an 80% drop in seropositivity, while 28 showed decreased anti-receptor binding domain (RBD) and anti-spike (S) IgG titers, with a GeoMean NT50 neutralization titer dropping to 163.5. As an NT50 > 100 is known to confer protection from SARS-CoV-2 re-infection, our data show that the neutralizing activity elicited by the natural infection has lasted for at least 10 months in a large fraction of subjects.