https://phys.org/news/2019-01-whatsapp-tackle-fake-news-problem.html

But the problem that this story and others like it pose is real. Rumours, hoaxes and misinformation find fertile breeding ground on social media. But as Google, Facebook, Twitter and other social media platforms increasingly crack down on misinformation, the purveyors of false stories are seeking refuge on direct messaging apps such as WhatsApp.

In developed countries, WhatsApp is primarily used as a personal messaging app. But in developing countries many people rely on it as a social network. Here, it's not uncommon to join groups with hundreds of members. People follow groups dedicated to topics ranging from interests in sports and entertainment to media and politics, often finding them through websites such as the Brazilian Grupos de Zap. Despite WhatsApp's limitation of 256 members per group, thousands of groups can exist at any given time dedicated to a political candidate, party or a social movement.