Q: What is the meaning of a status change from "Round one (a review is overdue)" to "Round two (awaiting reviewer comments)"?
I have send my research for possible publication; after 45 days the status changed from round one (a review is overdue) to round two (awaiting reviewer comments). Really, I didn’t understand how the journal can jump to the the second round review stage without sending me any comments from the first round to make the suggested corrections?
I doubt that the paper went out to review for a second round before you had input. Likely, the journal felt it needed another reviewer after the overdue review was never obtained. Alternatively, they could have given a time extension to the overdue reviewer. In any case, contact your associate editor or the editor to explain the status to you.
Status descriptions and their meanings vary from journal to journal. It can sometimes be difficult to understand what they mean. I don't think the paper would be sent out for a second round of review without sending you the reviewer comments first. One possibility is that since there was a delay in the review, the paper was sent to a different reviewer without waiting too long for the overdue review. Thus, the two rounds here would refer to the two different times reviewers were assigned for your paper.
However, for more clarity, you can consider writing to the journal editor asking for an update on the current status.
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