About the Authors
National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
London School of Hygiene and Tropical Medicine, London, United Kingdom
The authors have declared that no competing interests exist.
Conceived and designed the experiments: MP UP AC CS. Analyzed the data: MP CS AC. Contributed reagents/materials/analysis tools: MP AC CS JT UP. Wrote the first draft of the manuscript: MP. Contributed to the writing of the manuscript: MP AC CS JT UP. ICMJE criteria for authorship read and met: MP AC CS JT UP. Agree with manuscript results and conclusions: MP AC CS JT UP.