Nineteen-Year Evidence on Measles-Mumps-Rubella Immunization in Mexico: Programmatic Lessons and Policy Implications.

Area of Science:

• Public Health
• Vaccinology
• Epidemiology

Background:

• Measles vaccine introduced in Mexico in 1971; last endemic transmission in 1995.
• Monovalent measles vaccine replaced by measles-mumps-rubella (MMR) in 1998.
• MMR vaccination schedule: two doses at 12 months and either 18 months or 6 years.

Purpose of the Study:

• Evaluate the performance of Mexico's measles-mumps-rubella (MMR) and measles-rubella (MR) vaccination programs.
• Analyze trends in vaccine coverage and data consistency across major health institutions (IMSS, ISSSTE, SSA) from 2006-2024.
• Identify systemic challenges impacting vaccination program effectiveness and population immunity.

Main Methods:

• Retrospective analysis of secondary data from 2006 to 2024.
• Review of vaccine procurement and administration records from IMSS, ISSSTE, and SSA.
• Comparison of administered doses against procurement targets and national/international data (WHO, ENSANUT).

Main Results:

• Significant inconsistencies between MMR vaccine procurement and administration, with a deficit of 22.5 million doses (25% of target) between 2006-2024.
• Suboptimal national MMR coverage with substantial year-to-year and inter-institutional variability.
• Marked discrepancies with WHO and ENSANUT data; measles outbreak in 2025 and high mumps incidence indicate significant immunity gaps.

Conclusions:

• Systemic challenges in Mexico's MMR vaccination program include procurement-administration mismatches, overestimated coverage, and unclear MR targets.
• Immunity gaps confirmed by the 2025 measles resurgence and high mumps incidence, highlighting missed vaccination opportunities.
• Recommendations include improved planning, harmonized coverage estimates, robust monitoring, and prioritizing MMR for catch-up campaigns.