The exact etiopathology of chilblains observed during the Coronavirus Disease 2019 (COVID-19) pandemic is still unclear. Initially, SARS-CoV-2 appeared as the obvious causing agent, but two years of various investigations have failed to convincingly support its direct implication. Most affected individuals have no detectable virus, no anti-SARS-CoV-2 antibodies and no symptoms of COVID-19. Analyses of skin biopsies similarly failed to unambiguously demonstrate presence of the virus or its genome. In a recent hypothesis, SARS-CoV-2 would cause the lesions before being promptly eliminated by unusually strong type I interferon responses. With others, we feel that environmental factors have not been sufficiently considered, in particular cold exposure related to unprecedented containment measures. The cause of pandemic chilblains remains a stimulating puzzle which warrants further investigation.
De Greef, A., Coulie, P., & Baeck, M. (2022). Pandemic chilblains: Are they SARS-CoV-2-related or not? Clinical Immunology, 237, 108984 [1-3]. https://doi.org/10.1016/j.clim.2022.108984 (Original work published 2022)