I came across this article which features a new Coursera course. COVID-19 Contact Tracing (offered by Johns Hopkins) provides a promotion option right now which enables you to earn a free Course Certificate. As stated in the FAQ section, “you will need to enroll via a web browser on either a computer or a mobile device and not via the Coursera mobile app to enroll for the course and certificate for free. Unfortunately, the promotional price is not redeemable through the mobile app”.
If you have not taken the course, don’t miss the chance! If you’ve already taken the course, feel free to share your takeaway in the comment section.
(It was edited to add some more info.)