Coming out of lurker status to say that for anyone who was waitlisted/not accepted at JH, it's definitely disappointing, but try again next year!
Last year I applied and was rejected - it was a major bummer. I spent the next 12 months getting more experience, picking up extra tasks at work to gain demonstrable skills, volunteering outside of work for PH-related organizations, generally beefing up the resume any way I could, and fine tuning my application essay. Re-applied this year and got in, and you can, too!