News stories use stock images all the time. It’s perfectly normal, especially when a story is health-related, or in other contexts where privacy and confidentiality are important.

If the person in the image is the same person who the text is about, there will be a caption which says so. (Or will give other identifying information, like the date and location of the photo, as appropriate.) If it’s a stock image, any reputable news source will include a note which says so.