Preparing for malaria vaccine introduction
The most recent WHO malaria mortality estimate is 627 000 deaths for the year 2012. While this represents an estimated 42% reduction in global malaria mortality rates since 2000 in association with a large scaling up of WHO recommended preventive, diagnostic and treatment measures, there remains a need for additional preventive measures including vaccines. As one candidate malaria vaccine has reached the regulatory evaluation stage, GACVS considered the need for post-licensure safety assessment for when malaria vaccines become available for public use.
GACVS considers that the development of recommendations for post-licensure safety assessment of malaria vaccines is an important preparatory step, in order to provide early implementing sites with sufficient time for planning, training and improving or developing surveillance systems. Early identification of sites would also have the benefit of allowing the establishment of active surveillance for events of special interest, thereby providing background rates for those events prior to vaccine introduction. GACVS noted that the safety guidance would be developed alongside effectiveness and impact guidance and that it was important to ensure harmonisation with this guidance, as it is likely that studies could be designed to examine the impact of both safety and effectiveness. GACVS also noted the guidance was intended for use by the public sector of implementing countries to assist them to conduct independent studies and be prepared to assess data obtained by the manufacturer.
GACVS discussed the principal elements of such recommendations and suggested that the main components should cover on-going strengthening of routine systems for reporting adverse events following immunization (AEFIs), stimulated passive reporting in selected settings, such as health demographic surveillance system sites and active follow-up for specific events of interest using suitable epidemiological designs – such as case control, self-controlled case series and cohort event monitoring – to enable testing of hypotheses and quantification of risks. These components would allow detection and evaluation of signals for rare unexpected events as well as assessment of events of interest from clinical trials – in particular febrile convulsions and meningitis. It was noted that it is important that lessons are learnt from the experience in Africa of safety studies for meningococcal serogroup A vaccine introduction, but that a key difference was that the vaccine would probably be introduced with a routine schedule rather than through large mass campaigns. It was also noted that it is important that the guidance balances the need for high quality studies with what is feasible in the settings where these studies are likely to be done. This includes, for example, use of case definitions adapted to local clinical practice. Further discussion focused on the importance of considering rare but serious events and possible mechanisms for following up vaccine recipients such as diary cards, issuing of mobile telephones or identifying patients through hospital admissions. It is expected that a guidance document will be available in mid-2015.