ABVC Diphtheria in The ASEAN Region Focus Report 2025

Diphtheria is a bacterial infection primarily targeting the upper respiratory tract and skin, causing severe complications like heart and nervous system damage. The bacterium produces a toxin that can result in severe complications, including damage to the heart and nervous system. Although diphtheria is preventable through vaccination, maintaining immunity requires a complete primary series and booster doses. Unvaccinated or undervaccinated individuals remain vulnerable, with 30% of unvaccinated cases fatal without appropriate treatment, especially in young children (WHO, 2024a). During the 1970s, diphtheria cases and deaths in low- and middle-income countries were around one million and 50,000 to 60,000 deaths were reported annually. However, following the launch of the Expanded Programme on Immunization in 1974, which included diphtheria among its six initial vaccines, significantly reduced the global incidence of diphtheria, with over 90% of reported cases falling between 1980 and 2000 (WHO, 2017a). In 2023, global estimates indicated that 84% of children received the recommended three doses of diphtheriacontaining vaccines during infancy, with 16% unvaccinated or incompletely vaccinated, highlighting significant disparities in vaccine coverage across countries (WHO, 2024a). Countries around the world, including ASEAN member states, have a vision and mission to achieve elimination and control on vaccine preventable disease including diphtheria in the WHO Southeast Asia Region by 2026, as outlined in the WHO Southeast Asia Regional Vaccine Implementation Plan 2022-2026. This report provides an overview of Diphtheria, including its transmission, symptoms, and treatment, as well as current data on incidence and mortality. It also focuses on the regional situation within ASEAN, analysing the impact of the disease and the region's collective efforts to control it through surveillance, rapid response, and public health initiatives. Through this focus, the aim of the report aims to highlight the critical role of prevention and preparedness in reducing the burden of tuberculosis across vulnerable populations.