title: Effect of age on the incidence of aseptic meningitis following immunization with monovalent mumps vaccine.
abstract: OBJECTIVE
  The purpose of this study was to determine the risk of aseptic meningitis after mumps vaccination in younger children compared with older children.
  
  
  METHODS
  This prospective cohort study included a total of 21,465 children under 18 years of age who had received the first dose of three of the Japanese mumps monovalent vaccine. We compared the cumulative incidence of aseptic meningitis for 30 days after vaccination among the following age groups: ≤ 1, 2, 3-4, and ≥ 5 years old. We also investigated the cumulative incidence of salivary gland swelling, a fever (≥ 38°C) lasting at least 3 days during the 10 to 25 days following immunization, vomiting of 3 times or more, headache, and seizure.
  
  
  RESULTS
  A total of 10 aseptic meningitis, 551 salivary gland swelling, 844 fevers, 669 vomiting, 757 headaches, and 29 seizure cases were identified. The cumulative incidence of aseptic meningitis increased with age (0.016%, 0.021%, 0.066%, and 0.096%, respectively). Statistical significance was observed between children ≥ 3 years old and those < 3 years of age [0.078% vs. 0.018%, RR 4.35 (95% CI 1.05-18.2), p=0.04]. The cumulative incidence of salivary gland swelling also increased with age (1.8%, 3.0%, 3.5%, and 4.5%, respectively). For non-specific adverse events, the cumulative incidence of fever or seizure decreased with age. In contrast, the cumulative incidence of headache increased with age. The cumulative incidence of vomiting was similar among children ≤ 4 years of age; however, that in those children ≥ 5 years old was significantly lower.
  
  
  CONCLUSIONS
  The first dose of mumps vaccine that is currently available for use in Japan may be administered in children less than 3 years of age in order to complicate a less aseptic meningitis after immunization.
authors.affiliation: Department of Pediatrics, Iizuka City Hospital, Iizuka, Japan; The Committee of Immunization of the Society of Ambulatory and General Pediatrics of Japan, Japan. Electronic address: qze05346@nifty.com.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Muta
authors.affiliation: Nagai Pediatric Clinic, Takamatsu, Japan; The Committee of Immunization of the Society of Ambulatory and General Pediatrics of Japan, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Nagai
authors.affiliation: Ito Pediatric Clinic, Kurume, Japan.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Ito
authors.affiliation: National Hospital Organization, Mie Hospital, Tsu, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ihara
authors.affiliation: Laboratory of Viral Infection, Kitasato Institute for Life Sciences, Tokyo, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nakayama
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005334:Fever / Q000209:etiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008297:Male; D008582:Meningitis, Aseptic / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D009108:Mumps Vaccine / Q000009:adverse effects*; D011446:Prospective Studies; D012307:Risk Factors; D012469:Salivary Glands / Q000503:physiopathology; D012640:Seizures / Q000209:etiology; D014611:Vaccination
chemical_list: D009108:Mumps Vaccine
keywords: Adverse events; Age; Aseptic meningitis; Mumps vaccine