Investigating the characteristics of mumps outbreaks in Fujian Province, China
Ruihong Wu1, Zhifei Chen1, Xiuhui Yang1
1Fujian Provincial Key Laboratory of Zoonosis Research, Fujian Provincial Center for Disease Control and Prevention, Fuzhou, China.
Objectives:
Identifying the specifics and potential causes of mumps outbreaks in the Fujian Province during the period of 2017 to 2022.
Methods:
Mumps cases reported by the National Notifiable Communicable Disease Report System (NNCDRS) in China during the observation period of the 5 years were investigated annually and by age to detect homogeneity of the spread of the disease over time. If specific age-peaks may appear, we investigated those figures by analysing group characteristics in mumps cases presented as outbreaks. Those characteristics include demography (age and sex), clinical symptoms, place and time identification, and vaccination status. Regarding the latter, it was hypothesized that cases manifesting an outbreaks and appearing in young adults should have a low vaccination coverage, and a long-lasting period since they received their vaccine.
Results:
The total number of mumps cases reported during the observation period was 15,294, leading to incidence rates ranging from 3.2/100,000 to 8.0/100,000 per year. In the older age-group the disease spread by year and age (9 to 15y old) manifested 20 outbreaks accounting for 710 cases, all happening during 2017 to 2019. Thereafter those outbreaks disappeared in that age-group. The group characteristics specified that all the outbreaks happened in school settings, with a median age of 13y (range 6 to 19y). Parotid gland enlargement was observed in 82.7 %. The median duration of the outbreaks was 28 days, varying from 14 to 74 days. Only 27.6 % of the cases received at least one dose of the MuCV vaccine, and among these vaccinated individuals, 94.9 % developed mumps more than 5 years after vaccination. The dramatic reduction in outbreaks after 2019 could be explained by the public health measures taken during the COVID period and/or the new vaccination policy implemented in 2008 (free vaccination, 1 dose) and 2020 (2 doses) of young children causing therefore a lower rate of circulation of the virus.
Conclusion:
Mumps outbreaks observed in young adults during 2017-2019 causing a disease peak, indicated a potential link to unsatisfactory vaccination coverage with prolonged interval since receiving the vaccine. As those disease peaks disappeared since 2020, close monitoring for new outbreaks in young adults is recommended that may initiate a new vaccination strategy for that age-group.
Insights
Mumps outbreaks in Fujian Province (2017-2019) were linked to low vaccination coverage in young adults. Outbreaks ceased post-2019, possibly due to public health measures and updated vaccination policies, warranting ongoing surveillance.
Area of Science:
- Epidemiology
- Public Health
- Infectious Diseases
Background:
- Mumps outbreaks pose a significant public health challenge, particularly in school-aged populations.
- Understanding the specific drivers of mumps outbreaks is crucial for effective control strategies.
Purpose of the Study:
- To identify the characteristics and potential causes of mumps outbreaks in Fujian Province, China, between 2017 and 2022.
- To analyze age-specific incidence and outbreak patterns to inform public health interventions.
Main Methods:
- Retrospective analysis of mumps cases reported to the National Notifiable Communicable Disease Report System (NNCDRS).
- Investigation of outbreak characteristics including demography, clinical symptoms, location, timing, and vaccination status.
- Age-specific analysis to identify peaks and investigate group characteristics during outbreaks.
Main Results:
- A total of 15,294 mumps cases were reported, with incidence rates varying annually.
- Twenty mumps outbreaks occurred between 2017 and 2019, primarily affecting individuals aged 9-15 years in school settings, with 710 cases.
- Low vaccination coverage (27.6%) and waning immunity (94.9% infected >5 years post-vaccination) were noted in outbreak cases; outbreaks ceased after 2019.
Conclusions:
- Mumps outbreaks in young adults (2017-2019) were associated with suboptimal vaccination coverage and prolonged intervals since vaccination.
- The decline in outbreaks post-2019 may be attributed to COVID-19 public health measures and improved childhood vaccination policies.
- Continued surveillance for mumps in young adults is recommended, potentially leading to revised vaccination strategies for this demographic.
