Ask HN: Could someone make a contact tracing app

Singapore has a contact tracing app, but we all could use one, if we get into proximity with someone else (with the app) for a number of seconds and close distance it logs it, if a person gets sick he logs it in the app and all people who got into contact the last x days receive a warning. as far as i know it does not exist yet. Companies could ask all employees to install the app.