"Officials from the Iowa Department of Public Health are sending messages to people who have had sexual contact with patients being treated in their hospitals, usually through Facebook Messenger, Grindr, Tinder, and other online dating apps.
Health workers from Iowa are using dating apps like Grindr and Tinder in order to trace people who have potentially been exposed to different sexually transmitted diseases like chlamydia and gonorrhea."
https://z6mag.com/2019/07/29/grindr-tinder-used-to-track-potential-std-patients-to-warn-them/
This seems like a great idea to help people get treated quickly, and to prevent spreading STDs further.