The rate of anaphylaxis for the Pfizer vaccine is around 11 people in a million. Anaphylaxis is an extreme allergic reaction. The vast majority, if not all, of those cases involve people who are allergic to one of the ingredients in the vaccine. It's possible for anyone worried about allergy to have a pre-vaccination discussion with a health professional who specialises in allergy. To give this context, you need to consider the adverse reactions to any medical procedure. Could be to an anaesthetic at the dentist or before an operation, or to having a CT scan or an MRI scan, or a chest X-ray, or donating blood, or having a blood test, or taking paracetamol. I had an operation on my lumbar vertebrae a few years ago. Before I "went under," the surgeon leaned over me, said that there was a one in 300 chance of my dying on the operating table, and did I still want to go ahead. Too bloody right I did: I'd suffered excruciating pain for years.

Can't speak for the US, but here every vaccination centre has someone there at all times who is trained to deal with the emergency of anaphylaxis. Unless you know of an allergy to a vaccine ingredient, using the extremely remote risk of anaphylaxis as an excuse to not have the jab is unacceptable.