title: Analysis of public concerns about influenza vaccinations by mining a massive online question dataset in Japan.
abstract: Elucidating public concerns regarding vaccinations is important for successful immunization programs. The objective of the present study was to categorize public concerns regarding influenza vaccinations in Japan by analyzing a massive web-based question dataset.
  
  
  
  The Yahoo! Chiebukuro (Japanese Yahoo! Answers) Dataset, which includes more than 16 million questions collected between April 2004 and April 2009, was used in this study. We sequentially filtered data to obtain questions on influenza vaccinations. Any questions that met our exclusion criteria concerning veterinary vaccines or computer virus vaccines were removed from the analysis. Filtered questions and their answers were manually analyzed for their content by a team of board-certified pediatricians.
  
  
  
  After filtering data, we obtained 1950 questions regarding influenza vaccinations. The three most frequently asked questions were regarding the vaccination schedule, safety, and effectiveness. When we analyzed monthly trends in question contents, we noted the emergence of similar questions in the same period every year. Therefore, we classified the time periods of each year into three parts: (1) from April to the commencement of seasonal influenza vaccinations (September), (2) from October until the epidemic period, and (3) the epidemic period. Two interesting results were obtained: concerns regarding effectiveness abruptly increased during the epidemic period, and pregnant or breastfeeding women increasingly asked questions regarding feasibility between October and the epidemic period.
  
  
  
  The questions and concerns collected and analyzed in this study illustrate that the public have questions about the influenza vaccine and also that questions changed with periodical consistency. These results highlight the possible usefulness of providing the public with the latest and correct information to their questions in a timely manner, for example via an official health website.
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan. Electronic address: nawa@ped.med.osaka-u.ac.jp.
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Nawa
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Shigetoyo
authors.initials: S
authors.lastname: Kogaki
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Ishida
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Baden
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Katsuragi
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Narita
authors.affiliation: Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Tanaka-Taya
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ozono
mesh_terms: D057225:Data Mining; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007115:Immunization Schedule; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000517:prevention & control; D007564:Japan; D010353:Patient Education as Topic; D011247:Pregnancy; D011639:Public Opinion; D011795:Surveys and Questionnaires; D014611:Vaccination / Q000523:psychology*
chemical_list: D007252:Influenza Vaccines
keywords: Big data; Influenza vaccinations; Public concern; Vaccination coverage; Vaccine confidence