Measles as tracer and tugboat: Why eradication can strengthen immunization systems.

As measles resurges globally, we face an important strategic choice. Large outbreaks reflect declining vaccination coverage, inequities in health services access, conflict, population displacement, vaccine hesitancy, and inadequate investment in immunization programs. However, measles is more than a vaccine-preventable disease. Because of its extraordinary transmissibility, it functions both as a tracer of weaknesses in immunization systems and public health infrastructure, and as a potential tugboat for strengthening them.The Immunization Agenda 2030 highlights strong immunization systems, equitable service delivery, and effective surveillance as foundations for controlling vaccine-preventable diseases. Bill Foege, a leader of smallpox eradication, argued that measles eradication could reduce health inequalities while acting as a "tugboat" that pulls stronger immunization systems into place. This perspective is increasingly relevant. The capacities required for measles eradication, including high routine immunization coverage, sensitive surveillance, quality laboratory networks, rapid outbreak response, community engagement, and political accountability, are also fundamental to resilient health systems and preparedness for future pandemics.Rather than competing with health-system strengthening, measles eradication can accelerate it. The current resurgence should be viewed not only as a warning signal of system fragility but also as an opportunity to strengthen immunization systems, advance health equity, and renew commitment to global eradication.