Varicella outbreak in a highly-vaccinated school population in Beijing, China during the voluntary two-dose era

Details

• Alternative Title:
  Vaccine
• Personal Author:
  Suo, Luodan ; Lu, Li ; Wang, Qinghai ; Yang, Fan ; Wang, Xu ; Pang, Xinghuo ; Marin, Mona ; Wang, Chengbin
• Description:
  Background
  
  Two-dose varicella vaccination has been available in Beijing since 2012 in the private sector. We investigated a varicella outbreak in a highly vaccinated elementary school population.
  
  Methods
  
  A cohort study was carried out and a varicella case was defined as an acute onset of generalized maculopapulovesicular rash without other apparent cause in a student attending the school from March 29 through May 17, 2015. Breakthrough varicella was defined as varicella >42 days after the last vaccine dose among both 1- or 2-dose varicella vaccine recipients. Vaccination information was collected from immunization records; information on prior varicella and clinical presentations was collected by surveying students’ parents.
  
  Results
  
  Of the 1056 students in the school, 1027 (97.3%) reported no history of varicella. Prior to the outbreak, 98.6% of students had received ≥1 dose of varicella vaccine, and most (63.2%) students received two doses. Twenty varicella cases were identified for an overall attack rate of 2.0%. Half of the cases occurred in the classroom of the index case-patient, a two-dose recipient who was not isolated after symptom onset. Breakthrough varicella accounted for 95% of cases (19/20) with attack rates of 14.3% (1/7), 1.6% (6/362) and 2.0% (13/649) among unvaccinated, one-dose, and two-dose students, respectively. Most case-patients (18/20, 90%) had <50 lesions. No difference in clinical presentations was found between one-dose and two-dose recipients with breakthrough varicella.
  
  Conclusion
  
  Moderate two-dose varicella vaccine coverage was insufficient to prevent a varicella outbreak. Two-dose recipients with breakthrough varicella are contagious. High two-dose varicella vaccine coverage and timely isolation of cases may be needed for varicella outbreak prevention in the two-dose era.
  
  
• Subjects:
  Chickenpox Vaccine Child Child, Preschool Cohort Studies Disease Outbreaks Female Herpesvirus 3, Human Humans Immunization Schedule Incidence Male Parents Risk Factors Schools Students Surveys And Questionnaires Vaccination Vaccination Coverage

  More +
• Source:
  Vaccine. 35(34):4368-4373
• Pubmed ID:
  28684165
• Pubmed Central ID:
  PMC5555361
• Document Type:
  Journal Article
• Funding:
  CC999999/Intramural CDC HHSUnited States/
• Place as Subject:
  Beijing, China
• Volume:
  35
• Issue:
  34
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:c502f0ecd6a9b268d47d6793e8621b56f7cfc4107e284dade45f91d4ff867f13
• Download URL:
  https://stacks.cdc.gov/view/cdc/47538/cdc_47538_DS1.pdf
• File Type:
  [PDF - 736.55 KB ]