Q: What does a change from "Under review" to "Reviewer request completed" and back to "Under review" mean?

Detailed Question -

I submitted my paper to an Elsevier journal. It was sent out to one reviewer only and the editor gave a moderate revision decision. After resubmission, it changed to "Under review" after 12 days, and then "Reviewer request completed" after another 3 days, but it changed to "Under review" again after 7 days. What does it mean?

1 Answer to this question
Answer:

Your revised paper was probably first sent to the same reviewer who had reviewed it initially. This was when the status changed to "Under review." Once the reviewer submitted his/her report, the editor must have felt that he/she needed an additional review to be able to make a final decision on your paper. The editor, therefore, sent out another reviewer request/ invitation. This is when the status changed to "Reviewer request completed." Once the new reviewer responded and accepted the request to review your paper, the status once again changed to "Under review." 

This is a process most journals follow and you have nothing to worry about. Once this review comes in, the status will probably change to “With Editor” or “Decision in process.”

Related reading: