The paper by T Jefferson and colleagues (Feb 26, p 773),1 which reviews the efficacy and effectiveness of influenza vaccines in healthy children, contains much valuable information, particularly in identifying non-English-language studies. However, there are two important areas, both relating to children younger than 2 years, where the paper conveys messages that are potentially misleading and likely to be misconstrued by the mainstream media. These are first, the use of the terms vaccine effectiveness and vaccine efficacy, and second, the way in which results that do not reach levels of conventional statistical significance are reported and discussed.