A twitter observation suggests that some people’s understanding of what goes in the Introduction to a paper is different from mine.

In my view, you are citing things in the Introduction to indicate what motivated you to do the study and to give some insight into why you are using these approaches. Anything that was published after you wrote the manuscript did not motivate you to conduct the study. So there is no reason to put a citation to this new work in the Introduction. Unless, of course, you do new experiments for a revision and can fairly say that they were motivated by the paper that was published after the original submission.

It’s slightly assy for a reviewer to demand that you cite a manuscript that was published after the version they are reviewing was submitted. Slightly. More than slightly if that is the major reason for asking for a revision. But if a reviewer is already suggesting that revisions are in order, it is no big deal IMO to see a suggestion you refer to and discuss a recently published work. Discuss. As in the Discussion. As in there may be fresh off the presses results that are helpful to the interpretation and contextualization of your new data.

These results, however, do not belong in the Introduction. That is reserved for the motivating context for doing the work in the first place.