What is vaccine hesitancy?

Vaccine hesitancy is not the same as complete refusal; it includes uncertainty, delay, and selective acceptance. The World Health Organization has identified it as a major threat to global health because it can undermine immunization programs and allow preventable diseases to return. Causes include mistrust, misinformation, fear of side effects, access barriers, and low perception of disease risk. Public health responses often combine clear communication, community trust, and easier access to vaccines. Understanding hesitancy is important because vaccination is both a medical and social intervention.