Skin manifestations of COVID-19: impact of SARS-CoV-2 variants and potential for early diagnosis and epidemiological surveillance (review)

During the evolution of SARS-CoV-2, new genetic variants emerged that differed in virulence, infectivity, and clinical manifestations. The WHO classifies them for epidemiological monitoring as variants of concern (VOC) and variants of interest (VOI). In particular, the Delta and Omicron variants showed different frequencies of respiratory symptoms and severity of the disease. As the pandemic progressed, the number of reports of dermatological symptoms increased, which in some cases appeared earlier than the classic signs of COVID-19. Further study of skin manifestations may contribute to improving diagnostics and epidemiological surveillance. Objective — to summarize data on the nature of skin manifestations of COVID-19 and circulating variants of the SARS-CoV-2 virus, as well as to evaluate skin manifestations as potential markers for early detection of infection and their role in the epidemiological surveillance system. Materials and methods. Bibliosemantic and analytical approaches were used. The information base was publications from the scientometric databases PubMed, Scopus, and Web of Science, which included the results of meta-analyses, reviews, original studies, and clinical observations on skin manifestations of COVID-19. The search was carried out using the following keywords: «COVID-19», «SARS-CoV-2», «skin manifestation», «early symptoms», «surveillance», «rash», «cutaneous signs». Results and discussion. During the circulation of the Alpha and Beta variants, the prevalence of skin manifestations remained stable, and among them the most frequent were maculopapular, urticarial and vesicular rashes, as well as vascular-type lesions. According to reviews and case registries, some dermatological symptoms preceded respiratory ones and varied depending on the severity of the disease — feathery changes were observed in mild cases, and retiform purpura — mainly in hospitalized patients. During the Delta wave, the frequency and duration of skin manifestations, including skin burning and acral rash, were higher compared to the Omicron period, with skin burning being the most diagnostically significant symptom. Monitoring skin manifestations of COVID-19 may be a valuable tool to support diagnosis and track changes in the interaction between the virus and herd immunity. In a number of cases, skin manifestations of COVID-19, particularly in the pediatric population, were the first or only clinical signs of infection, highlighting the potential of dermatological examination as a means of early clinical detection of the disease. In conditions of limited access to in-person consultations during quarantine measures, telemedicine technologies provided effective remote diagnosis of dermatological symptoms. Integrating dermatological monitoring, including using telemedicine, into the epidemiological surveillance system may contribute to the timely detection of COVID-19 cases. Conclusions. Skin manifestations of COVID-19 may serve as additional diagnostic markers, especially in cases of limited access to testing. Their frequency and nature vary depending on the SARS-CoV-2 variant. The evolution of the virus is accompanied by a transformation of dermatological symptoms, which requires dermatologists to be aware of typical clinical patterns. The integration of dermatologists into the epidemiological surveillance system can contribute to the timely detection of cases and the containment of the spread of infection. Detection of skin signs may also improve clinical management and prognosis of COVID-19.