Lisa,
That's a good question. A simple fix, is to re caulk and see if that works.
If the shower has been leaking for some time, there could be damage behind the drywall. In general, if the leak is fairly recent, it will most likely be OK.
A sign that things could be worse, would be soft flooring near the shower base, Loose tiles, Holes in the tile backer and so on.
Terry

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