title: Commentary: Extending the boundaries of data collection by mail.
authors.affiliation: Institute of Social and Preventive Medicine, University of Geneva,and Quality of Care Unit, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: T V
authors.initials: TV
authors.lastname: Perneger
authors.forename: J F
authors.initials: JF
authors.lastname: Etter
mesh_terms: D015981:Epidemiologic Factors; D006509:Hepatitis B / Q000453:epidemiology; D006801:Humans; D011159:Population Surveillance / Q000379:methods*; D011177:Postal Service; D012463:Saliva / Q000821:virology; D016036:Seroepidemiologic Studies