I had the same with Tramadol as it happens, Jos. Without realising it, I became physically dependent on it in less than three weeks. I didn't realise it until I skipped a couple of doses during a day out. The cold turkey phase was the worst three days of my life. I was so animated about it that I went back to the doc to give him a bollocking. But codeine and tramadol are narcotics that can make you dependent. Vaccines are neither narcotic nor do they cause dependency. If you've had adverse reactions to vaccines in the past, beyond the regulation sore arm or feeling off-colour for a short while, it's as likely as not that you were allergic to a non-active ingredient. The doctor should be able to advise you as to whether that could happen again. Overall, it pays to be careful who you listen to. The area round here is replete with scaremongers and downright cranks.