Pete, my understanding is that the concerns expressed by some (only a minority to be fair) isn't to do with the immediate effects of the jabs, but their possible longer term impacts upon the cardio-vascular health of some people.
Similarly, what has spiked some unsettledness is the intransigence of the pharmaceutical companies with being transparent about question of whether they might have prioritise ethical concerns over the interests of their shareholders.
Russell Brand has 'amusingly' (!not to everyone's taste!) summarised some of the key concerns regarding the pharmaceutical companies avoidance of answering some quite reasonable questions that people - including elected representatives - have/want to ask.
Mmmh. Well there are no doubt some people who, if about to die of thirst in a desert, would decline a glass of water without written assurance that it had not passed through any lead pipes because of the long term risk of cumulative lead poisoning.