title: A sham case-control study of effectiveness of DTP-Hib-hepatitis B vaccine against rotavirus acute gastroenteritis in Kenya.
abstract: BACKGROUND
  In many GAVI-eligible countries, effectiveness of new vaccines will be evaluated by case-control methodology. To inform the design and assess selection bias of a future case-control study of rotavirus vaccine effectiveness (VE) in western Kenya, we performed a sham case-control study evaluating VE of pentavalent vaccine (DTP-Hib-HepB) against rotavirus acute gastroenteritis (AGE).
  
  
  METHODS
  From ongoing rotavirus surveillance, we defined cases as children 12 weeks to 23 months old with EIA-confirmed rotavirus AGE. We enrolled one community-based and two hospital-based control groups. We collected vaccination status from cards at enrollment, or later in homes, and evaluated VE by logistic regression.
  
  
  RESULTS
  We enrolled 91 cases (64 inpatient, 27 outpatient), 252 non-rotavirus AGE facility-based controls (unmatched), 203 non-AGE facility-based controls (age-matched) and 271 community controls (age-matched). Documented receipt of 3 pentavalent doses was 77% among cases and ranged from 81-86% among controls. One percent of cases and 0-2% of controls had no pentavalent doses. The adjusted odds ratio of three versus zero doses for being a case was 3.27 (95% CI 0.01-1010) for community controls and 0.69 (95% CI 0.06-7.75) for non-rotavirus hospital-based AGE controls, translating to VE of -227% and 31%, respectively, with wide confidence intervals. (No facility-based non-AGE controls were unvaccinated.) Similar results were found for ≥2 pentavalent doses and for severe rotavirus AGE.
  
  
  CONCLUSIONS
  The study showed that it is feasible to carry out a real case control in the study area, but this needs to be done as soon as the vaccine is introduced to capture the real impact. Sham case-control or pilot studies before vaccine introduction can be useful in designing case-control VE studies.
authors: Kenya Medical Research Institute (KEMRI)/Centers for Disease Control and Prevention (CDC) Research and Public Health Collaboration, Kisumu, Kenya. skhagayi@kemricdc.org.
authors: Sammy
authors: S
authors: Khagayi
authors: Jacqueline E
authors: JE
authors: Tate
authors: Reuben
authors: R
authors: Onkoba
authors: Umesh
authors: U
authors: Parashar
authors: Frank
authors: F
authors: Odhiambo
authors: Deron
authors: D
authors: Burton
authors: Kayla
authors: K
authors: Laserson
authors: Daniel R
authors: DR
authors: Feikin
mesh_terms: D016022:Case-Control Studies; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000627:therapeutic use*; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D018073:Haemophilus Vaccines / Q000627:therapeutic use*; D017325:Hepatitis B Vaccines / Q000627:therapeutic use*; D006801:Humans; D007223:Infant; D007297:Inpatients; D007630:Kenya; D016015:Logistic Models; D008297:Male; D010045:Outpatients; D015995:Prevalence; D012107:Research Design; D012401:Rotavirus; D012400:Rotavirus Infections / Q000453:epidemiology / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000008:administration & dosage
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines; D017325:Hepatitis B Vaccines; D014613:Vaccines, Attenuated; C122182:diphtheria-tetanus-acellular pertussis-Hib-hepatitis B vaccine