Changes and Predictions of Mumps Incidence in China: A Time Series Model with Intervention Approach

Background: Whether vaccine-preventable, non-TB respiratory infections in China underwent COVID-19-era declines followed by rapid post-reopening rebounds remains uncertain.Methods: We analyzed monthly mumps notifications from the National Health Commission of China (2010-01 to 2023-07).A SARIMA-intervention model incorporating the Oxford Stringency Index (SI) assessed associations between policy stringency and notifications and generated forecasts after reopening (2022-12).A counterfactual SARIMA trained on pre-pandemic data (2010-01 to 2019-11) estimated expected notifications absent COVID-19-related measures.We compared observed values, intervention-model predictions, and counterfactual forecasts.Results: Mumps displayed bimodal seasonality with an overall downward trend and baseline shifts around 2012, 2017, and 2020.An unusual rise occurred in 2017 (peak increasing from 20,096 to 33,458), followed by a historic low in 2020 (peak 15,211).After COVID-19 onset, observed notifications dropped sharply below counterfactual forecasts-by 81% in April 2020 and 89% in December 2022.Wilcoxon tests showed significantly lower monthly notifications in 2020-2022 versus 2010-2019 (P<0.001 each year).In the intervention model (1,1,0)(1,1,0)[12], SI was not significantly associated with notifications (=-17.41,95% CI -41.75 to 6.93; P>0.05).Interventionmodel predictions aligned with observed data during the pandemic and showed no immediate rebound after reopening.Conclusions: In contrast to reports for tuberculosis, mumps notifications did not rebound immediately post-reopening, and declines were not statistically attributable to SI. Expanded vaccination (including a two-dose schedule since 2020), pathogen-specific dynamics, unchanged reporting, sustained protective behaviors, and a limited post-reopening window may explain the pattern.Ongoing vaccination and surveillance are warranted to guide post-pandemic control strategies.