The answer to your question: confirmation bias
I completely agree with that!
There is a LOT of bias in research, wo even going in the issue of why only the positive research are actually published and not the other 20 negative ones, and for me this IS the reason why I am always cautious when I read 'Oh such and such research has shown that xxx'. And why some people can be weary of the line 'But research has shown that ...' because tbh, if 50% of research can't be replicated, then as far as I am concerned, it means 50% of what we think we know isn't the truth (or rather we can not say it IS the truth. It might be or it might not. We don't know).
For one thing, I can not understand how it is possible to say that all children should be vaccinated when we all know (?) that not every drugs is suitable for any patient.
No one would ever say that all people who have headaches have to take let's say paracetamol or ibuprofen. Because we know that
1- some people react badly to them (eg: some 1000 people die every year from gastro intestinal issue following a course of NSAD)
2- they don't always work (eg they actually do cause headaches...)
3- well they just have side effects varying depending on the condition of the patient, incl the issue of association with other medications.
So why why should we assume that all children should have all the vax at the age given by the NHS (or whatever other health authority it is)? And that there can't be any side effects? Or that these side effects are just mild, they can't be that serious?
In the same way, we would all agree that it is the patient choice to follow (or not) a consultant advice regarding their illness. It is OK for a pg woman to say no to an induction or for a cancer patient to have such and such treatment.
So, why is it suddenly 'bad, irresponsible etc...' to actually use of our own free choice to choose to have a vax (or for our dc to have a vax)? Is that OK to force everyone to have a drug even if you know that X amount of patients will die from it/develop a serious illness? Even if if this number of people is very low? (Very important Ethical question there btw.)
Why is it that, as parents/patients, we are never shown the list of possible side effects and contra indications for vax?
I always read the ones on any medication I take. When I was taking some drugs to treat endometriosis, I knew from that list a side effect was high blood pressure (not that my consultant ever said a word about it...). When I was rushed to hospital with very bad headaches etc..., I could tell what was the cause.
Now what about vax? Have you ever been told about possible side effects (apart from the 'Oh he might feel a bit under the weather...') or contra indications? I do not believe these are the only possible side effects or contra indication for them but no one ever wants to honestly talk about it with patients (That's the result of the bias that 'vax are good for you' there). Sensible discussion wo anyone putting down the other would probably go a really long way to reassure parents who are worried or avoid any feeling of 'conspiraty' or 'big pharmas are just there to make money not to make people better'.
This whole subject of vax has become a very emotive issue. And everyone finds it easy to twist results etc... to make them say what they want.
A good example for me is the MMR.
I went to see paed for ds as he had chronic constipation. He had it since just after he had the first MMR. I raised the issue with the paed who, of course, told me 'But there is no link between the MMR and the vax. We haven't proven that there is any link'. (Add pissed off face and annoyed tone of voice)
I said 'Yes. But we haven't proven that there is no link either'.
He stayed silent for a bit and just said 'no, we haven't.' And that's right, the answer is we don't know. Not having found the link yet doesn't mean there is no link.