这就是前几天有人介绍过的 Moderna Arm

https://bbs.wenxuecity.com/health/961154.html

https://www.usatoday.com/story/news/health/2021/01/27/covid-arm-moderna-vaccine-rash-harmless-side-effect-doctors-say/4277725001/

An angry red rash being called “COVID arm” is a harmless but annoying response in some people who get the Moderna vaccine. Aside from sometimes being itchy, it doesn't appear to be dangerous, and people who get it should not hesitate to get their second dose of the vaccine, doctors say.

There is no indication the reaction is anything but a topical – and brief – response as the body’s immune system goes to work, said Dr. Esther Freeman, director of global health dermatology at Massachusetts General Hospital.

“We want to reassure people that this is a known phenomenon," she said. "Having a big red splotch on your arm for a couple of days may not be fun but the reality is there's no need to panic and no reason not to get your second shot."