To minimise external factors that could bias our findings, the descriptive analysis focussed only on GSK vaccines that are formulated using the same technology and for which long-term data are available.
A search of the GSK clinical studies (available fromhttps://www.gsk-studyregister.com/en/ ) identified clinical studies of vaccines containing inactivated hepatitis A antigen, either as standalone HAV (Havrix; GSK, Belgium) or combination HAB (Twinrix; GSK, Belgium). Studies with at least 10 years of follow-up of antibody persistence data were included, as well as any longer-term follow-up of these studies using mathematical modelling [8 (link), 9 (link)]. In order to extrapolate outcomes in children using data in adults, studies with data on adult vaccine doses of HAB 720 EU or HAV 1440 EU were selected. The group of subjects in the children study given paediatric doses of HAB 360 EU [12 (link)] was excluded as this dose is not used in clinical practice. Children were defined as anyone aged under 18 years old, as the recommended inactivated vaccination dose and schedule is the same for this age group.
All procedures in the studies involving human participants were performed in accordance with the Good Clinical Practice Guidelines, as defined by the International Conference on Harmonization, the Declaration of Helsinki and its later amendments or comparable ethical standards.
A search of the GSK clinical studies (available from
All procedures in the studies involving human participants were performed in accordance with the Good Clinical Practice Guidelines, as defined by the International Conference on Harmonization, the Declaration of Helsinki and its later amendments or comparable ethical standards.