It is a not a live vaccine, so cannot give you any sort of illness. It does not actually kick in for about 10-12 days after receiving it, so if you have anything in your system prior to having it, or catch something in that first week,you will feel unwell (not the vaccine), Do think some people have a pyschosomatic reaction to this vaccine, expecting to feel ill afterwards.
Well the leaflet for this year’s over-65 adjuvanted vaccine states quite clearly that during clinical trials, very common side-effects have been observed (headache, muscular pain, pain at injection site) as well as common ones (including nausea, diarrhoea, fever, generally feeling unwell).
Our pharmacist warned us when we had our vaccinations that people had reported these to him as well.
We’ve been lucky like you and not had symptoms in previous years, but I have never thought that those who had were imagining it! Just as well, as this year DH and I had some of the common side-effects (headache, upset stomachs, fatigue) starting the same evening. And as we hadn’t been anywhere else for quite some time beforehand, it’s pretty certain that they were related to the jabs.
Obviously being mildly unwell is a very small price to pay for the protection given by the vaccine, but side-effects do actually happen!