Would just emphasise by repeating what Suedonim has said. When you have the 'flu jab (whichever type), the protection does not kick in for about a fortnight afterwards. Cannot get flu or a cold, etc from this jab, but as your immune system may be working hard, anything you have picked up before getting the jab, may make you feel unwell.
There does seem to be some shortages of the over-65's vaccine, no idea why. The chemist where I normally have mine each year has not even contacted me yet - but I did get it done at the pharmacy at my local Sainsbury, and they said they were running out fast. Had no effect at all from it, not even a slightly sore arm.
I live by myself and really fear getting influenza. Nothing at all like a cold, heavy or otherwise. Just feeling so very ill and unable to move or get out of bed. Getting to my en-suite toilet feels virtually impossible.
Must say, have not had flu since I started having these jabs each year.