What measles reveals about health security in Southeast Asia

While the Ebola outbreak (Opens in new window) in the Democratic Republic of Congo and Uganda commands headlines due to its deadly and exotic nature, the risk of the virus spreading widely is epidemiologically low – little comfort for those dealing with the immediate consequences, but a relief for the wider world with still-fresh memories of a global pandemic.

But the threat from virus infections remains very real – and in a region much closer. The resurgence of measles in Southeast Asia reveals more about the state of regional health security than a distant outbreak ever could.

Measles is not an emerging disease. It is among the most extensively studied vaccine-preventable diseases in public health. A safe and highly effective (Opens in new window) vaccine (Opens in new window) has been available for decades. Measles was one of the first diseases targeted when the World Health Organization launched the Expanded Programme on Immunisation (EPI) in 1974, and vaccination has subsequently become part of routine childhood immunisation across Southeast Asia. Therefore, when measles returns at scale, it reflects weaknesses in health systems – not scientific uncertainty, unlike the situation in the early days of Covid-19 when uncertainty itself led to poor outcomes.

Measles outbreaks are increasingly viewed as a sensitive indicator of health-system performance. Working towards elimination requires consistently high vaccination coverage, effective surveillance, strong primary healthcare, and public confidence in immunisation programs. Unlike Ebola, which primarily tests emergency preparedness and outbreak response capacities, measles tests whether health systems can reliably perform their most fundamental functions over time: vaccinating children, reaching underserved populations, and sustaining routine healthcare delivery, therefore maintaining public trust.

Recent trends across Southeast Asia are concerning. The Western Pacific Region recorded a 743% increase (Opens in new window) in measles cases between 2022 and 2024. The most recent data (Opens in new window) revealed that from January to May 2025 Vietnam reported more than 81,000 suspected measles cases. Cambodia reported 2,150 cases between January and April 2025, while the Philippines reported more than 2,000 cases during the first months of that year. WHO and UNICEF attribute much of the resurgence to immunity gaps (Opens in new window) created during (Opens in new window) and after the COVID-19 pandemic.

The scale of these outbreaks should prompt reflection on how health security is understood in the region. Since Covid-19, governments have invested heavily in epidemic intelligence by establishing laboratory networks and employing genomic surveillance. This supported emergency preparedness mechanisms and maintaining its investments remains essential (Shet et al., 2022). Yet preparedness for extraordinary events does not necessarily translate into resilience in routine public health functions. The pandemic exposed how gains in emergency response can coexist with declining childhood vaccination coverage and widening inequalities in access to essential services (Opens in new window).

This exposes a fundamental tension in contemporary health security thinking. Much of the post-pandemic discourse has focused on future threats: the next pandemic, the next zoonotic spillover, or the next Ebola-like emergency. Yet health security is ultimately sustained through ordinary institutions rather than exceptional interventions. Resilient health systems (Opens in new window) depend not only on surveillance and emergency response capabilities but also on strong primary healthcare, routine immunisation programs, reliable supply chains, and trusted relationships between communities and health authorities.

Measles reveals whether countries and their health systems have truly recovered from Covid-19, including their ability to reach missed children, protect vulnerable communities, and rebuild vaccine confidence.

This challenge is inherently regional. Increased mobility through tourism, labour migration, and economic integration across Southeast Asia mean that immunity gaps in one country can quickly become vulnerabilities elsewhere. The effectiveness of one country’s measles control effort is linked to the performance of neighbouring health systems, as infectious diseases do not recognise national borders.

For the Association of Southeast Asian Nations (ASEAN), the policy implications are significant. Regional health cooperation has understandably prioritised pandemic preparedness since Covid-19. However, the current measles resurgence suggests that preparedness frameworks should place equal emphasis on strengthening routine immunisation systems. Investments in surveillance and laboratory capacity remain important. But they cannot substitute for vaccination outreach, community engagement, and strong primary healthcare.

Indeed, immunisation programs should increasingly be viewed as health security infrastructure. They build trust, generate surveillance data, and create delivery platforms that can be mobilised during future emergencies. Strengthening routine immunisation therefore improves both current health outcomes and future pandemic preparedness.

In this sense, measles functions as a governance audit for health systems. It reveals whether states can convert policy commitments, financing, and surveillance capacity into routine population protection. While global attention remains focused on Ebola, a more revealing test of regional resilience is unfolding much closer to home.

Measles is not the next pandemic. But its resurgence suggests that health security ultimately depends less on preparing for exceptional threats than on sustaining the ordinary institutions that prevent known ones.