Owing to formal links established between the Cochrane Collaboration and the World Health Organization (WHO), I was contacted by Steven Wiersma and Jördis Ott and invited to present our findings in Geneva to the experts working on hepatitis A vaccine policy. Our contribution strengthened several existing recommendations when measured against the GRADE criteria, but also identified a number of gaps in existing knowledge, thus raising questions that required further investigation. These included the need for more evidence on the effects of single doses of both inactivated and live attenuated vaccines; evidence on the efficacy and safety of the live attenuated vaccine with fewer risks of bias; and a review of the evidence on long-term protection.