I do not see the bias, all the more so given that the whole article after that first paragraph very clearly explains that further investigation is taking place

I do not see the bias, all the more so given that the whole article after that first paragraph very clearly explains that further investigation is taking place to determine whether there is such a causal link. I have no idea whether conferring is a strictly defined term in the context of clinical research, but even if it is this is not a scientific journal article but aimed at the general public. Going in detail to the claim that 'appear to confer' is biased, even if we take such a strict understanding of confer, compare the semantic effect of affirming and negating the sentence with and without 'appear to' 1. 'the vaccines conferred protection' 2. 'the vaccines did not confer protection' 3. 'the vaccines appeared to confer protection' 4. 'the vaccines did not appear to confer protection' Which of the sentence above is closest to the truth, and which is most inaccurate?