About the Authors
Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, London, United Kingdom
Department of Mathematics and Statistics, Strathclyde University, Glasgow, United Kingdom
Respiratory & Systemic Infection Laboratory (RSIL), Health Protection Agency, London, United Kingdom
RG and CS have received support from Wyeth vaccines (now Pfizer) for conference attendance. SF, PW, AJVH, ES, NA, and EM declare no competing interests.
Analyzed the data: SF NA. Wrote the first draft: SF AJVH EM. Wrote the manuscript: SF AJVH LS PW CS RG EM. ICMJE criteria for authorship read and met: SF AJVH LS PW CS RG EM NA. Agree with the results and conclusions: SF AJVH LS PW CS RG EM NA. Designed the study: AJVH NA EM. Oversaw the field work: LS. Database design and study data management: PW. Culture and serotyping: CS RG.