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Skin symptoms, like systemic symptoms, differ by COVID-19 variant, according to a large retrospective study that compared clinical data from more than 300,000 participants in the United Kingdom during the Omicron and Delta waves.
Among the key findings, the study shows that skin involvement during the Omicron wave was less frequent than during the Delta wave (11.4% vs. 17.6%), skin symptoms generally resolved more quickly, and that the risk for skin symptoms was similar whether patients had or had not been vaccinated, according to a team led by Alessia Visconti, PhD, a research fellow in the department of twin research and genetic epidemiology, King’s College, London.
These data are consistent with the experience of those dermatologists who have been following this area closely, according to Esther Freeman, MD, PhD, associate professor of dermatology at Harvard Medical School and director of MGH Global Health Dermatology at Massachusetts General Hospital, both in Boston.
“Anecdotally, we thought we were seeing fewer skin symptoms with Omicron versus Delta and the ancestral strains, and now this study shows it is true,” said Freeman, who is also principal investigator of the American Academy of Dermatology’s International Dermatology COVID-19 Registry.
The data also confirm that the skin is less likely to be involved than in past waves of COVID-19 infections.
“Up to this point, it was hard to know if we were seeing fewer referrals for COVID-related skin rashes or if clinicians had just become more comfortable with these rashes and were not referring them as often,” added Freeman, who was among the study coauthors.
Data Captured From 348,691 Patients
The data from the study was generated by 348,691 users in the United Kingdom of the ZOE COVID study app, a smartphone-based tool introduced relatively early in the pandemic. It asked users to provide demographic data, information on COVID-19 symptoms, including those involving the skin, and treatments. Of 33 COVID-related symptoms included in the app, five related to the skin (acral rash, burning rash, erythematopapular rash, urticarial rash, and unusual hair loss).
While the focus of this study was to compare skin manifestations during the Omicron wave with the Delta wave of COVID-19, the investigators also had data on the experience in 2020 with wild-type COVID-19 that preceded both variants. Overall, this showed a stepwise decline in skin symptoms overall, as well in as skin symptoms that occurred in the absence of systemic symptoms.
“The shift in the skin manifestations makes sense when you think about the change that is also being seen in the systemic symptoms,” said Freeman, referring to lower rates of cough and loss of smell but higher rates of sore throat and fatigue. “Omicron is achieving immune escape, which is why there is a shift in involved tissues,” she said in an interview.
Previous data collected during the wild-type COVID-19 stage of the pandemic by the same group of investigators showed that 17% of patients reported skin rash as the first symptom of COVID-19 infection, and 21% reported skin rash as the only clinical sign of infection.
In the Delta and Omicron waves, skin rash was an isolated initial symptom in only 0.8% and 0.5% of patients, respectively. (The authors noted that, in the United Kingdom, the first documented samples of the Delta variant were detected in October 2020, and the first documented samples of the Omicron variant were detected in November 2021.)
During the early stages of wild-type COVID, an acral rash was characteristic, occurring in 3.1% of patients, according to the U.K. data. In the Delta wave, acral rashes, at an incidence of 1.1% remained positively correlated with a diagnosis of COVID-19 infection. In the Omicron wave, acral rashes were observed in only 0.7% of patients and were no longer statistically correlated with a positive COVID diagnosis.
Characteristic Cutaneous Symptoms Are Evolving
Early in the course of the COVID-19 epidemic, more than 30 types of rashes were observed in patients with COVID-19 infection. Cutaneous symptoms continue to be diverse, but some, such as acral rash, are being seen less frequently. For example, the odds ratio of a positive COVID-19 diagnosis among those with an erythematopapular rash fell from 1.76 to 1.08 between the Delta and Omicron waves.
While specific cutaneous symptoms are less predictive of a diagnosis of COVID-19, clinicians should not discount cutaneous symptoms as a sign of disease, according to Veronique Bataille, MD, PhD, a consultant dermatologist at King’s College.
“You need to keep an open mind” regarding cutaneous signs and a diagnosis of COVID-19, Bataille, one of the coauthors of the U.K. report, said in an interview. In general, she considers a low threshold of suspicion appropriate. “If the patient has no past history of skin disease and no other triggers for a rash, then, in a high prevalence area, COVID must be suspected.”
In most cases, the rash resolves on its own, but Bataille emphasized the need for individualized care. Even as the risk of life-threatening COVID-19 infections appears to be diminishing with current variants, cutaneous manifestations can be severe.
“There are cases of long COVID affecting the skin, such as urticaria or a lichenoid erythematopapular rash, both of which can be very pruritic and difficult to control,” she said.
Freeman echoed the importance of an individualized approach. She agreed that most cutaneous symptoms are self-limited, but there are exceptions and treatments vary for the different types of skin involvement. “I think another point to consider when examining skin lesions is monkey pox. The fact that these are overlapping outbreaks should not be ignored. You need to be alert for both.”
Visconti, Freeman, and Bataille reported no potential conflicts of interest.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.