Authors' response: Meningococcal vaccine antigen diversity in global databases.

To the editor: We concur with Anderson et al. [1] that estimates of the coverage of the protection elicited by novel meningococcal protein vaccine formulations are dependent on knowledge of cross-reactivity. Indeed, we stressed this point in our penultimate paragraph of our article [2], where we referenced the surrogate assays developed by two companies to address this issue for their particular formulations.