Serological Mumps Evaluation of Medical Students in Catalonia (Spain): Is a Third Dose of Vaccine Needed?

While measles-mumps and rubella vaccines (MMR) have reduced mumps incidence, outbreaks continue to occur in developed countries. The aim of the study was to evaluate the serological status against mumps and its association with vaccination history among medical students in Catalonia (Spain). A cross-sectional study was conducted during 2023-2025 among medical students attending four university teaching-units. Participants completed a questionnaire and provided blood samples for mumps IgG testing. Associations between positive serology and vaccination status and the independent variables were assessed calculating adjusted OR (aOR) and 95% confidence interval (CI) after adjustment for age, sex, and degree year. Among 235 participants, 94.5% had received 2-MMR doses, and 94.9% had been vaccinated more than 15 years earlier. Complete vaccination was associated with being a 5th-year student (aOR 5.45; 95%CI: 1.38-21.50); 80.4% showed positive IgG, being higher in women (aOR 2.52; 95%CI: 1.20-5.30). Seropositivity declined with increasing time since last vaccination. Although the proportion of students serologically protected is acceptable, more than 15 years have passed since the last vaccine dose in most of the students and waning immunity is expected. The recommendation of a third MMR dose for medical students and healthcare workers in mumps outbreak settings should be considered.