Erratum

Upon publication of the original article [1], it was noticed that the Acknowledgements Section was missing. The acknowledgements should read as, “The authors would like to thank the following individuals for helpful comments on an earlier version of the study manuscript: David Savitz, Julien Beauté, Pasi Penttinen, and Kevin Pottie. In addition, the authors would like to acknowledge the contributions of the Centers for Disease Control and Prevention (CDC), which provides financial support to the World Health Organization Initiative for Vaccine Research (U50 CK000431).” This has now been acknowledged and corrected in this erratum.