COVID-19 Vaccine Induced Radiation Recall Phenomenon

Soyfer, Viacheslav; Gutfeld, Orit; Shamai, Sivan; Schlocker, Albert; Merimsky, Ofer

Radiation Recall Phenomenon (RRP) is an uncommon, late occurring, acute inflammatory skin reaction that emerges in localized areas coincident with previously irradiated radiotherapy (RT) treatment fields. RRP has been known to be triggered by a number of chemotherapy agents. To the best of our knowledge, this report is the first description of RRP following administration of the Pfizer-BioNTech vaccine for COVID-19, or any other currently available vaccine against COVID-19. Acute skin reactions were observed in two radiotherapy patients with differing timelines of RT and vaccinations. In both cases however, the RRP presented within days of the patient receiving the second dose of vaccine. For each RT course the treatment planning dosimetry of the radiation fields was compared to the area of the observable RRP. RRP developed within the borders of treatment fields where prescription dose constraints were prioritized over skin sparing. Our observation is currently limited to two patients. The actual incidence of RRP in conjunction with Pfizer-BioNTech vaccine or any other vaccine against Covid-19, is unknown. For cancer patients being treated with radiation with significant dose to skin, consideration should be given to the probability of RRP side-effects from vaccinations against COVID-19.