It was obvious this would happen when I looked at the first rounds of trial data used to approve the vaccines. In the placebo group, we find that nausea, headache, non-specific myalgia, etc. are all common reported side-effects, in some cases nearly as common as the non-placebo group.<p>And then we had the media prime us with stories of people taking a day to recover after the injection, etc. The power of suggestion is quite real. It can turn a minor discomfort into something not even noticed, or into something that makes a person quite miserable for a couple days.
The same can be said for the effectiveness of the vaccine. I don't see any evidence that the "effectiveness" of the vaccines is anything beyond the placebo effect.