Back in February WhatsApp for iOS introduced a Screen Lock feature, that, when enabled, would make the app immediate you to authenticate the usage of Touch ID every time you wanted to enter it. Now, many months later, the same thing has finally made it to Android, even though at the moment the functionality is solely section of the trendy WhatsApp beta build.

WhatsApp 2.19.221 is accessible for beta testers, and if you have it you can go to Settings > Account > Privacy > Fingerprint lock to enable the new feature. After you turn it on, you will want to use your fingerprint to authenticate each single time you choose to launch the app. You can nevertheless answer calls if WhatsApp is locked. It's no longer completely sure that if you have this version you will see the new setting, as it might additionally be tied to a server-side switch.