The same neural network can be trained for both problems. Advances in medical image neural networks translate to advances in people detecting neural networks.
Of course, they are not directly used without changing the training data, etc. However, if we look at the big picture to make a general statement, then the advances brought by Computer Vision on natural images often help push research on medical images forward, albeit with a year (or two) of delay. One such example is U-Net (https://en.wikipedia.org/wiki/U-Net).