Sex- and age-specific transmission pathways of mumps: a mechanistic SEPIAR modeling study in Chengdu, China (2008-2019).

INTRODUCTION

Despite widespread mumps vaccination, recurrent outbreaks persist globally, underscoring the need to clarify sex- and age-specific transmission mechanisms.

OBJECTIVES

This study characterizes mumps epidemiology in Chengdu (2008-2019) and quantifies sex- and age-specific transmission pathways using a mechanistic modeling framework.

METHODS

A sex- and age-structured Susceptible-Exposed-Pre-symptomatic-Symptomatic-Asymptomatic-Recovered (SEPIAR) model incorporating seasonal forcing was developed to estimate time-varying reproduction numbers (Rt) across 64 transmission pathways.

RESULTS

A total of 40,087 cases were reported (annual incidence: 21.72 per 100,000), with the highest burden among male students aged 5-14 and seasonal peaks in May-July and November-December. The model achieved good fit across demographic groups (R² = 0.13-0.73, P < 0.001). Females aged 10-14 exhibited the strongest transmission potential, particularly toward males aged 0-14 (median Rt: 1.18 to males 5-9; 0.75 to males 0-4; 0.55 within the same group). Sensitivity and empirical uncertainty analyses confirmed the robustness of these transmission patterns.

CONCLUSIONS

Sex and age may play an important role in shaping mumps transmission dynamics in Chengdu. The SEPIAR model may offer a useful framework for characterizing transmission pathways and identifying groups that could contribute disproportionately to spread. Interventions such as targeted vaccination during seasonal peaks, considering booster doses for females aged 10-14, enhancing surveillance in high‑incidence districts, and improving reporting capacity in rural areas could help reduce transmission and may support more effective and sustained mumps control in large urban settings.