WhatsApp Vaccine Discourse (WhaVax): An Expert-Annotated Dataset and Benchmark for Health Misinformation Detection

A new expert-annotated dataset of vaccine-related WhatsApp messages collected from large Brazilian public groups across multiple pandemic years. The dataset is built through careful keyword filtering, semantic deduplication, and a multi-stage annotation protocol with medical specialists, resulting in a reliable gold-standard corpus with substantial agreement. Dataset columns: Message: Message textgroup: Data related to the group in which the message was sentsender: ID of the person who sent the messageav1_desinfo, av2_desinfo, av3_desinfo, av4_desinfo: Labeling of each of the annotatorsis_quote: Whether this message is a reply to another messageddd_code: Area code of the person who sent the messagecountry_code: Country code of the person who sent the messagedate: Date and time the message was sentmessage_id: Message IDforwarded: Message forwarding level