Back in February WhatsApp for iOS added a Screen Lock feature, that, when enabled, would make the app prompt you to authenticate using Touch ID every time you wanted to enter it. Now, many months later, the same thing has finally made it to Android, although at the moment the functionality is only part of the latest WhatsApp beta build. WhatsApp 2.19.221 is available 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'll need to use your fingerprint to authenticate every single time you want...
Source: https://www.gsmarena.com/whatsapp_beta_for_android_adds_fingerprint_unlocking_support-news-38666.php
