Global health security refers to the measures and strategies taken to protect populations worldwide from infectious diseases, pandemics, and biological threats. Vaccination services play a critical role in this framework by preventing the spread of vaccine-preventable diseases, such as measles, polio, and influenza. Through immunization programs, health systems strengthen herd immunity, reduce mortality, and ensure communities are less vulnerable to outbreaks.In the context of global health security, vaccination services also involve rapid deployment of vaccines during public health emergencies, such as pandemics or bioterrorism events.