How to handle ethics review (IRB) when moving between institutions
When you change institutions, you will need approval from your new institution's IRB to continue any human subjects research. From their perspective, the new institution is about to "start" working on your existing project so they will review them as normal projects using their normal process. Of course, the review process might be different since the project is in process, data may have already been collected, etc. That may change the process of making a determination and might even change the determination, but it doesn't change the need for a determination.

This might lead to an interruption in your ability to conduct your research. As a result, you should contact your new IRB about any ongoing research project as soon as possible.

Depending on the stage of the project, the IRB could say one of many things. For example:


If you are still interacting or intervening with human subjects, you may need to either (a) submit brand new protocols for review or (b) have your new IRB delegate review to your previous institutions IRB. Both are common although the latter only really makes sense if your previous institution's IRB is going to continue overseeing the work (for example, because your have collaborators there).
If the project is at a stage where there is no further interaction or intervention, when data has been collected, and if data stored in a form where individuals are not identifiable, the IRB might say that you do not additional review at all since the work, at this stage no longer qualifies as human subject research. In my opinion, it's always better to let the IRB make that determination.
If data has been collected but if data continues to be identifiable or if analysis otherwise puts subjects at risk, you might need to put in a special request to analyze previously collected data. This is often a separate kind of application that can be a bit shorter and easier. I've had to do this even for projects that had been considered exempt at my previous institution.


As always, you are subject the rules of institution that is employing you. You should always check with them. I think it's not abnormal, in these situations, to set up a meeting with someone from the IRB to talk through these sorts of situations and make a plan of action.

[ For context, I am also a social scientist working in the United States. ]