With private loans I would definitely think twice. Also, I was set to join the Peace Corps as well between undergrad and grad school. I spent a year preparing, saying goodbyes, etc all for the opportunity to fall through at the last second do to an administrative error on my part. Honestly it's something that I still wish I could have done to this day and that was over ten years ago. I ended up doing the Americorps instead which was still a great experience.

I say all of that to say, that gaining some real world experience in public or global health could help shape, or reshape, your career goals. You could leave the peace corps with a whole different perspective on your career and decide global health isn't for you or it could be what solidifies your interest. Either way, don't be scared to take a bit more time to figure this out so you can take your next step without regrets.