[nudephil (OP)]

Here's a message from listener Kay:

I developed TB of the skin after having the BCG vaccination at about 8-10  yrs old. The smallpox vaccine before that also reacted strongly. I've never had a flu jab & am unsure about the COVID-19 vaccine, because I'm concerned about what might happen.

Any advice?

[Bored chemist]

Ask your doctor.

[evan_au]

Some vaccines are made with a weaker pathogen (eg cowpox was used as an early vaccine against smallpox).

If you have a compromised immune system, you may be affected by even a weakened pathogen.
- So it may be best for you to avoid a live virus vaccine (one of the candidate vaccines uses a monkeypox virus).
- There are a number of vaccine candidates that contain no living/infectious material (eg mRNA vaccines, or killed virus vaccines).

Some people also overreact to the adjuvant, which is intended to grab the attention of the immune system.

Again, talk to your doctor.