The RTS,S Clinical Trials Partnership have just published the results of the 18 month follow-up on protective efficacy of the GlaxoSmithKline (GSK) malaria vaccine RTS,S/AS01. These results have been eagerly awaited as they will be pivotal data for GSK in its regulatory submission for the vaccine and for the World Health Organization when it reviews the data on RTS,S and decides whether to recommend its use to malaria control programmes around the world.
The study showed that RTS,S provided protective efficacy, but that this waned over the 18-month follow-up period. Young infants (6-12 weeks at vaccination) seem to respond less well than children (5-17 months at vaccination). Vaccine efficacy in children at 18 months was 46%, and in infants was 27%. Clearly there is an effect in lives saved from the vaccine. It is unclear as to why young infants respond less well than children. However this vaccine is not a replacement for existing tools – vector control and effective diagnosis & treatment. Not only will its use be additive, but also its cost at a time when there are increasing strains on the funding of malaria control and elimination programmes. It is not yet clear if booster dosing will restore and prolong protection in the way that happens with more widely used vaccines. It will be a difficult call as to whether this vaccine can have a practical role for malaria programmes in many endemic countries, and exactly what that role will be.
The paper can be found in PLoS Medicine at this link: PAPER