Author Contributions: Drs Voordouw, Sturkenboom,
Dieleman, van der Lei, and Stricker had full access to the IPCI database.
All coauthors had full access to the data set for this study.
Study concept and design: Stricker, Voordouw,
Acquisition of data: Voordouw, van der Lei.
Analysis and interpretation of data: Stricker,
Voordouw, Sturkenboom, Dieleman, Stijnen, Smith.
Drafting of the manuscript: Stricker, Voordouw,
Critical revision of the manuscript for important
intellectual content: Stricker, Voordouw, Sturkenboom, Dieleman, Stijnen,
Smith, van der Lei.
Statistical analysis: Stricker, Voordouw, Sturkenboom,
Obtained funding: Stricker.
Study supervision: Stricker, Sturkenboom, Dieleman,
van der Lei.
Funding/Support: This study was supported by
an unconditional grant from the Netherlands Organisation for Health Research
and Development (ZonMw), project number 2200.0090. The grant was obtained
following review of a submitted protocol to evaluate the effectiveness of
the influenza vaccination program in Dutch elderly citizens. Dr D. J. Smith
was supported by European Union grant QLRT-2001-01034.
Role of the Sponsor: The sponsor had other
no influence on the design or conduct of the study.
Acknowledgment: We kindly thank Jan C. De Jong,
PhD, from the department of Virology, National Influenza Centre, Erasmus Medical
Center, for the use of the data for Table 2. We also kindly thank S. Salmaso,
MD, PhD, Instituto Superiore di Sanità, Rome, Italy, and I. S. M. Uhnoo,
MD, PhD, Medical Products Agency, Uppsala, Sweden, for their advice in preparing