key: cord-1019982-ww15y5w6 authors: Wei, Nancy; Fishman, Mary; Wattenberg, Debra; Gordon, Marsha; Lebwohl, Mark title: “COVID arm”: A reaction to the Moderna vaccine date: 2021-02-25 journal: JAAD Case Rep DOI: 10.1016/j.jdcr.2021.02.014 sha: 9fb6739314124e2376057eaa753189a58c0333c5 doc_id: 1019982 cord_uid: ww15y5w6 nan T he Moderna mRNA-1273 Q5 vaccine was authorized by the Food and Drug Administration for emergency use during the ongoing COVID-19 pandemic in December 2020. 1 Out of 15,185 participants in the phase III Coronavirus Efficacy (COVE) trials who received at least one dose of the Moderna vaccine, 228 (1.5%) reported hypersensitivity adverse events, including injection site rash and urticaria. 2 Although we have seen an eruptive, morbilliform rash that manifests 48 hours postvaccination that is similar to a drug rash (Fig 1) , we report 4 cases of ''COVID arm'': a localized erythematous rash surrounding the injection site that manifests days after the first dose of the Moderna COVID-19 vaccine. A 74-year-old woman with no history of medical conditions or allergies developed a pruritic, erythematous plaque with mild scaling on her left upper arm 8 days after the first Moderna vaccination (Fig 2) . There was no edema, calor, tenderness, or systemic symptoms. The rash spread to 15 cm in diameter over 10 days. After 1 week of treatment with topical clobetasol and oral cetirizine, the rash decreased in rubor and size but did not completely resolve. A 62-year-old woman with no significant medical history presented with a pruritic erythematous rash on her left deltoid 8 days after receiving the Moderna vaccine (Fig 3) . The rash began as a maculopapular eruption over the injection site and progressed in 3 days to an erythematous indurated plaque that was mildly edematous and warm to the touch. There was no associated pain, fevers, chills, or other systemic symptoms. The rash gradually receded after 3 days of treatment with mometasone ointment, diphenhydramine cream, and oral loratadine. The patient noted 2 recurrences lasting a few hours over the next 2 days that resolved with oral loratadine. A 54-year-old woman with no medical conditions presented with an erythematous, nonscaly patch on her left upper arm 7 days after the first dose of the Moderna vaccine (Fig 4) . The rash was nonpruritic and nonpainful and lasted for 4 days before resolving spontaneously. A 72-year-old woman with a history of psoriasis, atrial fibrillation, hypercholesterolemia, and hypothyroidism developed an erythematous patch on her left deltoid surrounding the injection site 10 days after the first dose of the Moderna. The rash was pruritic, warm to the touch, and measured 14 cm in diameter. After 2 days, the rash gradually decreased in size and calor Q6 and resolved without intervention. Photographs and reports of the ''COVID arm'' phenomenon several days after the first Moderna vaccine have recently appeared in social and public media. Consistent with our findings, patients experience a transient, pruritic rash that can present either as an urticarial welt or a macular erythematous patch in close proximity to the vaccination site 7 to 10 days after the first dose. 3 Two of our patients' rashes resolved without intervention, and the other 2 cleared with the use of topical steroids and/or oral antihistamines. There was no relation between development of the rash and patients' medical histories or allergies. Although the rash might be attributable to an immunologic response to the mRNA vaccine, it has not been reported as a reaction to other COVID-19 mRNA vaccines. 4 Both the Pfizer and the Moderna vaccines include polyethylene glycol, a known allergen, as well as other proprietary nonactive ingredients. [5] [6] [7] It is not known why this reaction has only been observed in recipients of the Moderna vaccine. In a nationally representative survey of 1676 US adults conducted in December 2020 by the Kaiser Family Foundation, 27% stated they would not get a COVID-10 vaccine even if it were available for free and deemed safe by scientists. 8 Among these, 59% cited worries about possible adverse events as a major reason for vaccine hesitancy. It is thus important for providers to reassure patients that ''COVID arm'' is a benign possible side effect that should not dissuade them from obtaining the Moderna vaccine. ''COVID arm'' is an uncommon adverse effect that can present as a localized, transient erythematous rash several days following the first dose of the Moderna COVID-19 vaccine. Although most cases resolve spontaneously, topical steroids and oral histamines have proven to be successful in clearing the rash and controlling symptoms. Providers should inform patients that COVID arm is a benign possible 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 COVID-19 vaccine: a comprehensive status report Clinical Trial Data Moderna COVID-19 Vaccine (EUA) Reactions and adverse events of the Pfizer-BioNTech COVID-19 vaccine j CDC Moderna COVID-19 vaccine EUA fact sheet for recipients and . (n.d.). Accessed February 9 Pfizer COVID-19 Vaccine EUA fact sheet for recipients and . (n.d.). Accessed February 9 Immediate-type hypersensitivity to polyethylene glycols: a review KFF COVID-19 vaccine monitor