About the Authors

Axel J. Schmidt

a.j.schmidt@rki.de

Affiliation Department for Infectious Diseases Epidemiology, Robert Koch Institute, Berlin, Germany

Jürgen K. Rockstroh

Affiliation Medical Clinic I, University of Bonn, Bonn, Germany

Martin Vogel

Affiliation Medical Clinic I, University of Bonn, Bonn, Germany

Matthias An der Heiden

Affiliation Department for Infectious Diseases Epidemiology, Robert Koch Institute, Berlin, Germany

Armin Baillot

Affiliation Governmental Institute of Public Health of Lower Saxony, Hannover, Germany

Ivanka Krznaric

Affiliation Medical Practice, Driesener Strasse, Berlin, Germany

Doris Radun

Affiliation Department for Infectious Diseases Epidemiology, Robert Koch Institute, Berlin, Germany

Competing Interests

The authors have declared that no competing interests exist, neither financial nor non-financial. Neither the German MOH, nor any pharmaceutical company had a role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The lecture fees and congress travel grants as disclosed by M.V. and J.K.R. have no connection to this case-control-study on sexual, nosocomial, and other non-sexual determinants. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials.

Author Contributions

Analyzed the data: AJS. Wrote the paper: AJS. Study design: AJS DR MV IK. Questionnaire: AJS DR. Clinical supervision: JKR. Recruitment of participants: MV IK. Statistical supervision: MadH DR. Antibody testing from DBS: AB.