Impact of Trivalent Viral Vaccination on the Incidence of Measles, Rubella, and Mumps in Paraguay, 2020-2025

Introduction: Vaccine-preventable diseases continue to represent a significant public health problem worldwide. Among them, measles, rubella, and mumps maintain their epidemiological relevance due to their high transmissibility and the potential to generate outbreaks in contexts of insufficient vaccination coverage. In Paraguay, the MMR (measles, mumps, rubella) vaccine is part of the national immunization schedule, as variations in coverage can influence the transmission dynamics of these diseases.Objective: To analyze the impact of measles, mumps, and rubella (MMR) vaccination on the incidence of measles, rubella, and mumps in Paraguay during the period 2020–2025.Methodology: An observational, ecological, retrospective, and cross-sectional study was conducted using secondary data from Paraguay's national epidemiological surveillance and vaccination records for the period 2020–2025. The sample consisted of reported cases of measles, rubella, and mumps, as well as annual MMR vaccination coverage records reported by the Ministry of Public Health's Expanded Program on Immunization. A descriptive analysis of the variables was performed using frequencies, percentages, and temporal trends. Furthermore, the evolution of vaccination coverage was compared with the incidence of the diseases during the study period to identify potential epidemiological associations.Results: Measles, mumps, and rubella (MMR) vaccination coverage decreased from 88% in 2020 to 85% in 2021, followed by a gradual recovery to 95% in 2024 and 94% in 2025. The incidence of measles and rubella remained at zero cases for almost the entire study period, with only 0.2 cases of measles recorded in 2025. Regarding mumps, the incidence increased from 12.5 cases in 2020 to 18.7 in 2022, coinciding with the years of lowest vaccination coverage, and subsequently decreased to 8.9 cases in 2025 as immunization rates improved. The results show an inverse relationship between MMR vaccination coverage and mumps incidence.Conclusion: The decline in MMR vaccination coverage was associated with an increase in mumps cases, while meals and rubella remained under control. Maintaining high vaccination coverage is essential to prevent the resurgence of vaccine-preventable diseases.