First shot I had a mild headache. This one gave me a bad headache the next day ( yesterday) . So following advice I rotated between Tylenol and Ibuprofen every four hours. No fever and no other symptoms. One day of not feeling good is a good trade off for some peace of mind. Yeah, I would do it again. Wife has had both and she had no side effects at all. I guess she is tougher and meaner than me.