A reply to the Letter to the Editor by Mäkelä, Herva and Nohynek in response to the article by Rerks-Ngarm S, Treleaven SC, Chunsuttiwat S, Muangchana C, Jolley D, Brooks A, Dejsirilert S, Warintrawat S, Guiver M, Kunasol P, Maynard JE, Biggs B-A, Steinhoff M. Prospective population-based incidence of Haemophilus influenzae type b meningitis in Thailand. Vaccine 2004;22:975-83.