title: Can the rolling cross-sectional survey design be used to estimate the effectiveness of influenza vaccines?
abstract: BACKGROUND
  Observational studies of influenza vaccine effectiveness often study persons seeking medical care for acute respiratory infection (ARI). We conducted a pilot study to determine if vaccine effectiveness could be estimated in the general population with a novel rolling cross-sectional survey sampling design and laboratory confirmation of influenza.
  
  
  METHODS
  Cross-sectional samples were selected weekly from defined populations in Marshfield, Wisconsin and Monroe County, New York from January through April, 2011 (12 weeks). Persons were telephoned and asked about the occurrence of ARI in the past week. Nasal and throat swabs were obtained from consenting individuals with ARI and tested by real-time reverse transcription polymerase chain reaction (RT-PCR). Vaccine effectiveness (VE) was defined as (100×[1-OR]) for vaccination in a logistic regression model that adjusted for age, calendar week, and site. The comparison group included all study participants without RT-PCR confirmed influenza, including those who were not ill.
  
  
  RESULTS
  Study personnel contacted 9537 (62%) of 15,303 persons sampled; the primary analysis included 5678 subjects. Of these, 193 (3%) reported an ARI and agreed to be tested for influenza; 13 (7%) were influenza positive. The adjusted effectiveness of the influenza vaccine was 1% (95% confidence limits -239-70%).
  
  
  CONCLUSIONS
  The rolling cross-sectional design is methodologically feasible and may be useful as a complement to clinic-based VE studies. This pilot study did not have sufficient power to detect significant vaccine effectiveness during a mild influenza season, but this approach may facilitate rapid estimation of VE in a pandemic setting when normal patterns of health care utilization are disrupted.
authors.affiliation: Marshfield Clinic Research Foundation, 1000 North Oak Avenue, Marshfield, WI 54449, USA. Electronic address: donahue.james@mcrf.mfldclin.edu.
authors.forename: James G
authors.initials: JG
authors.lastname: Donahue
authors.affiliation: Marshfield Clinic Research Foundation, 1000 North Oak Avenue, Marshfield, WI 54449, USA.
authors.forename: Burney A
authors.initials: BA
authors.lastname: Kieke
authors.affiliation: University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Szilagy
authors.affiliation: University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Blumkin
authors.affiliation: Marshfield Clinic Research Foundation, 1000 North Oak Avenue, Marshfield, WI 54449, USA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Hilgemann
authors.affiliation: Emory University, Department of Epidemiology, Biostatistics and Bioinformatics, 1518 Clifton Road, Atlanta, GA 30322, USA.
authors.forename: W Dana
authors.initials: WD
authors.lastname: Flanders
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Shay
authors.affiliation: Marshfield Clinic Research Foundation, 1000 North Oak Avenue, Marshfield, WI 54449, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Meece
authors.affiliation: University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gallivan
authors.affiliation: University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: John
authors.initials: J
authors.lastname: Treanor
authors.affiliation: Marshfield Clinic Research Foundation, 1000 North Oak Avenue, Marshfield, WI 54449, USA.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D009518:New York; D010865:Pilot Projects; D012107:Research Design
chemical_list: D007252:Influenza Vaccines
keywords: Influenza vaccine; Rolling cross section; Vaccine effectiveness