RNA-based COVID-19 Vaccine is Not a Contraindication to Phototherapy: Real-life Data on Minimal Erythema Dose Changes.

Dear Editor, After onset of the COVID-19 pandemics, the use of phototherapy for dermatological conditions became, as most systemic treatments in dermatology, a subject of debate; finally, several centers all over the world increased their COVID-19-preventive strategies to guarantee narrow band-UVB (NB-UVB) treatments to chronic patients. Nicastro et al. demonstrated that not only UV-C but also UV-B and UV-A have a powerful virucidal effect against SARS-CoV-2. Currently, it is not known whether the use of phototherapy during RNA-based COVID-19 vaccine is appropriate. Phototherapists may arbitrarily decide to discontinue NB-UVB when a COVID-19 vaccination is planned or has been administered. While the decision to discontinue NB-UVB is generally motivated by the fear of a potential, not yet fully understood, vaccine-related increase of the patients' photosensitivity, those who opt for continuing with UVB-NB act so hoping to prevent possible vaccine-related flares (i.e., psoriasis flares). To assess a potential decrease of minimal erythemal dose (MED), causing photosensitivity in NB-UVB patients who were administered a RNA-based COVID-19 vaccine, we performed the multicenter study described underneath. We prospectively evaluated 16 dermatological patients with psoriasis (PsO), atopic dermatitis (AD) or pruritus sine materia (Psn) who were planned to undergo at least one NB-UVB session (as a monotherapy) before being administered a RNA-based COVID-19 vaccine. The enrolled patients did not present relevant comorbidities in their medical history (in particular actinic keratosis, alcohol or tobacco addiction or porphyriae), did not take NBUVB contraindicated prescription drugs (e.g., retinoids), did not follow a specific diet (such as a vegan or a vegetarian diet). All recruited patients had completed in the past NB-UVB cycles without complications, showing high compliance (<2 session skipped and <2 rescheduled); also, they did not practice phytotherapy or any other alternative/complementary medicine practice. All patients underwent Minimal Erythemal Dose (MED) evaluation with Multiport UV Solar Simulator 601 (Solar Light CO.INC: Philadelphia, PA) at baseline (T0), 3 days after the first dose of vaccine (T1) and 3 days after the second dose of vaccine. In order to avoid systemic UVB-induced immunosuppression, NB-UVB was delivered three times a week by a Waldmann ramp equipped with 13 Philips TL100 W/01 fluorescent tubes (Waldmann Medizintechnik GmbH, VillingenSchwenningen, Germany) emitting 15 mW/cm at a distance of 20 cm as measured by a Waldmann UV meter dosimeter and was performed on a body surface area <80%. In line with clinical protocols to avoid photoadaptation phenomena, patients started with 70% of the MED with a session increase of 40% in absence of erythema—otherwise 10%—until a dose of 3.00 J/cm was reached. The dose was maintained constant in the following sessions. The sessions and the vaccinations were planned so that all patients would undergo a phototherapeutic session 2–5 h before vaccination and one session 3 days after vaccination. Patients' demographics and clinical characteristics are displayed in detail in Table 1. We enrolled five PsO patients (age: 37 [35–42] years), 3 AD patients (age: 53 [48.5–57] years) and 8 Psn patients (age: 44.5 [37.75–49.5]) with a Fitzpatrick skin type higher than II. In the recruited patient group, we assessed with Wilcoxon paired rank test MED oscillations which were neither statistically significant (p > 0.05) nor clinically meaningful; our results suggest that RNAbased COVID-19-vaccines do not increase photosensitivity and may rather induce photoadaptative phenomena; the latter could prove, however, detrimental for a proper phototherapeutic response. We suggest that upon a planned administration of a COVID-19-RNAVaccine neither a discontinuation nor a dose modification of a NBUVB treatment is needed. Also, all patients in our study displayed adequate levels of anti SARS-CoV-2 S1-Receptor Binding Domain (RBD) antibodies (test performed 15 days after vaccination).