There’s really no way to know this from the outside. It probably depends on a variety of factors. From the website:
On face, it’s ‘easier’ in the sense that you don’t need to have an advanced degree already or work experience before applying to the program - since the concurrent JD is that advanced degree, only in progress. But even though those aren’t required, JHU will probably still want some evidence that you are really interested in a public health career and will be looking for those things.
Also, just because it’s less common doesn’t mean it offers an improved rate - they may only get a small number of applications but may also accept only a very small number of people to that specific program.