Now, you do need to worry about WhatsApp chat as it will have a more secure fingerprint sensor in near future. Whatsapp is working towards to increase security by fingerprint sensor unlock technology that makes your chat more secure and private even when your phone screen is Unlocked.
WABetaInfo who is constantly making an eye on the beta update of Whatsapp, currently relive that company is working on fingerprint unlock technology to secure a WhatsApp application. Whenever this feature becomes available, you just need to enable by going into WhatsApp setting and privacy. Once enabling it, you will able to set up phone fingerprint lock as your WhatsApp lock.
Moreover, as a backup, they will provide you pin method in case you fingerprint does not work. So whenever you will open WhatsApp or click on its notification then every time you need to unlock WhatsApp by fingerprint.
This feature will be more secure and beneficial for the people who have some serious private messages and images.