Acknowledgments
icddr,b acknowledges the commitment of the Bill & Melinda Gates Foundation to its research efforts. icddr,b is also grateful to the Governments of Bangladesh, Canada, Sweden, and the UK for providing core or unrestricted support. The authors are grateful to all the parents and guardians of the infants who were enrolled and participated in this study. We thank the staff at the CDC for performing the neutralising antibody assays and the detection and measurement of poliovirus in faecal samples. We thank Harish Verma, WHO, for his participation in the initial planning visit for the study. We also thank John F Modlin of Dartmouth College (NH, USA) for his input during the initial discussions to design the study. We thank Keith Veitch (keithveitch communications, Amsterdam, Netherlands) for editorial assistance with the manuscript. This activity was reviewed by the CDC and was conducted consistent with applicable federal law and CDC policy.