Epidemiologic Analysis of Chilblains Cohorts Before and During the COVID-19 Pandemic.

Importance: Beginning in March 2020, case reports and case series linked the COVID-19 pandemic with an increased occurrence of chilblains, but this association has not been evaluated in an epidemiologic study. Objective: To assess whether a correlation exists between COVID-19 incidence and chilblains incidence. Design, Setting, and Participants: A retrospective cohort study was conducted within the Kaiser Permanente Northern California system from January 1, 2016, to December 31, 2020; health plan members of all ages were included. Exposure: COVID-19 incidence in 207 location-months, representing 23 geographic locations in northern California across 9 months. Main Outcome and Measures: Chilblains incidence was the main outcome. The association of chilblains incidence with COVID-19 incidence across the 207 location-months was measured using the Spearman rank correlation coefficient. Results: Of 780 patients with chilblains reported during the pandemic, 464 were female (59.5%); mean (SD) age was 36.8 (21.8) years. COVID-19 incidence was correlated with chilblains incidence at 207 location-months (Spearman coefficient 0.18; P = .01). However, only 17 of 456 (3.7%) patients with chilblains tested during the pandemic were positive for SARS-CoV-2, and only 9 of 456 (2.0%) were positive for SARS-CoV-2 within 6 weeks of the chilblains diagnosis. Test results of 1 of 97 (1.0%) patients were positive for SARS-CoV-2 IgG antibodies. Latinx patients were disproportionately affected by COVID-19 but not by chilblains. Conclusions and Relevance: This cohort study found that in northern California, the incidence of chilblains increased during the pandemic but was correlated weakly with the incidence of COVID-19 across 207 location-months. These findings may have resulted from a causal role of COVID-19, increased care-seeking by patients with chilblains during the pandemic, or changes in behavior during shelter in place.

Cutaneous manifestations of COVID-19: a systematic review and analysis of individual patient-level data.

Distinctive patterns in the cutaneous manifestations of COVID-19 have been recently reported. We conducted a systematic review to identify case reports and case series characterizing cutaneous manifestations of confirmed COVID-19. Key demographic and clinical data from each case were extracted and analyzed. The primary outcome measure was risk factor analysis of skin related outcomes for severe COVID-19 disease. Seventy-one case reports and series comprising 144 cases of cutaneous involvement in COVID-19 were included. The most frequently occurring morphologies were: morbilliform (30.6%), varicelliform (18.8%), urticarial (13.2%), chilblains-like (12.5%), and acro-ischemic (9%). The median age of patients was 51 years (mean: 45.9, range: 0 to 91). Patients with chilblains-like eruptions had lower frequencies of extracutaneous COVID-19 symptoms (5/18, 27.8%, P<0.05) and were less likely to have severe COVID-19 disease (2/18, 11%, 95% CI 1.4% to 34.7%, P=0.02). Patients with livedoid and acro-ischemic morphologies had severe COVID-19 more frequently than those with other morphologies (17/21, 81%, 95% CI 58.0% to 94.5%, P<0.0001). The most frequently observed cutaneous manifestations of COVID-19 (morbilliform, varicelliform, and urticarial) are well-described patterns of viral exanthems. However, chilblains-like, livedoid, and acro-ischemic morphologies are not traditionally associated with viral infections and were significantly associated with severity of COVID-19 disease.