ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) is the etiological agent of Coronavirus Disease 2019 (COVID-19), rapidly spread in the current pandemic. The diagnosis of Covid 19 is based on the detection of viral RNA by molecular amplification (NAAT) in nasopharingeal swabs and virus-specific antibodies of different isotypes in the serum. IgM and IgG anti-Sars CoV-2 appear 4-7 days after the onset of symptoms but the highest level of IgM and IgG are detected after 2-3 weeks and 3-6 weeks, respectively. Serological assays are useful for the diagnosis and for epidemiological studies. To compare different methods, we measured serum antibody levels with three automated assays including Elecsys®Roche anti-SarsCov2, Abbott Sars-CoV-2 IgG and Diasorin Liason®SARS-CoV-2 S1/S2 IgG in a goup of 50 selected subjects (negative or positive for nasopharingeal swab, initial screening with Abbott serological test or previuos clinical suspect of COVID-19). A good concordance of the results (68%) was found between Roche and Diasorin assays, and between Roche and Abbott tests while the concordance between Abbott and Diasorin is lower (38%). The samples were also analyzed with other 2 non automated assays: Euroimmun Sars-CoV-2 ELISA (IgG) and Euroimmun Sars-CoV-2 ELISA (IgA). The percentage of positivity is 58% with Diasorin Liason®SARS-CoV-2 S1/S2 IgG, 42% for Abbott Sars-CoV-2 IgG, 32% for Euroimmun Sars-CoV-2 ELISA (IgA), 30% for Euroimmun Sars-CoV-2 ELISA (IgG) and 28% for Elecsys® Roche anti-SarsCov2. The concordance of ~88% and 86% was revealed between Roche test and Euroimmun (IgG), and between Roche and Euroimmun (IgA), respectively, while it reduced to 66% among Diasorin and Euroimmun (IgG) and 62% between Abbott and Euroimmune (IgG).The results in agreement with all five tests were the 34% of total selected cases. The percentage of positive specimens tested with Roche method confirmed with at least 2 other assays was 100%;this value was 93% for Euroimmun (IgG), 81% for Euroimmun (IgA), 52% for Diasorin assay and 47% for Abbott test.
ABSTRACT
BACKGROUND: Acral chilblain-like lesions are being increasingly reported during COVID-19 pandemic. However, only few patients proved positivity for SARS-CoV-2 infection. The relationship between this skin manifestation and COVID-19 infection has not been clarified yet. OBJECTIVE: To thoroughly characterize a prospective group of patients with chilblain-like lesions and to investigate the possible relationship with SARS-CoV-2 infection. METHODS: Following informed consent, patients underwent (i) clinical evaluation, (ii) RT-PCR and serology testing for SARS-CoV-2, (iii) digital videocapillaroscopy of finger and toe nailfolds, (iv) blood testing to screen for autoimmune diseases and coagulation anomalies, and (v) skin biopsy for histopathology, direct immunofluorescence and, in selected cases, electron microscopy. RESULTS: Nineteen patients, all adolescents (mean age: 14 years), were recruited. 11/19 (58%) of them and/or their cohabitants reported flu-like symptoms one to two months prior to skin manifestation onset. Lesions were localized to toes and also heels and soles. Videocapillaroscopy showed pericapillary oedema, dilated and abnormal capillaries, and microhaemorrhages both in finger and toe in the majority of patients. Major pathological findings included epidermal basal layer vacuolation, papillary dermis oedema and erythrocyte extravasation, perivascular and perieccrine dermal lymphocytic infiltrate, and mucin deposition in the dermis and hypodermis; dermal vessel thrombi were observed in two cases. Blood examinations were normal. Nasopharyngeal swab for SARS-CoV-2 and IgG serology for SARS-CoV-2 nucleocapsid protein were negative. Importantly, IgA serology for S1 domain of SARS-CoV-2 spike protein was positive in 6 patients and borderline in 3. CONCLUSIONS: Chilblain-like lesions during COVID-19 pandemic have specific epidemiologic, clinical, capillaroscopic and histopathological characteristics, which distinguish them from idiopathic perniosis. Though we could not formally prove SARS-CoV-2 infection in our patients, history data and the detection of anti-SARS-COV-2 IgA strongly suggest a relationship between skin lesions and COVID-19. Further investigations on the mechanisms of SARS-CoV-2 infection in children and pathogenesis of chilblain-like lesions are warranted.