I would say very small considering it's a medical bag from 2012. I suppose it really begs the question of "When did the last batch of natives arrive at the island?".
Edit: They might not even be able to unzipper the thing, because they might not understand how it works. And if they go cutting into the bag to see what's in it, by the by, the bag'll start falling apart at the seams. I know from personal experience that that material is finicky stuff, and doesn't like being damaged. Or patched up, for that matter. <.<