[A red and swollen arm after vaccination for covid-19].

In this case report, we present a 41-year old male with a red rash on his arm 7 days post vaccination with the mRNA Moderna vaccine. While the patient received antibiotics for the suspicion of a cellulitis, this was actually a delayed type 4 local allergic reaction to the vaccine or a so called 'Covid arm'. This reaction occurs frequently, is usually self-limiting and a conservative treatment is recommended. Conflict of interest and financial support: none declared.