The WHO ‘Optimizing Immunization Schedules’ Project

The global vaccine schedule initially recommended by WHO (vaccination of children at 6, 10 and 14 weeks old for DTP-OPV and at 9 months old for measles) was established more than 25 years ago as part of the Expanded Programme on Immunization (EPI).

In spite of a global increase in vaccine uptake since then, vaccine-preventable diseases remain important causes of childhood morbidity and mortality.  However the epidemiology of the infections has changed. Also new vaccines have been (and will continue to be) introduced, health services have developed, and other interventions such as micronutrient supplementation and preventive treatments for malaria have become linked to EPI activity.  Meanwhile much has been learned about how vaccines can achieve maximum impact.

Given all this, there is growing recognition that the current schedule, and indeed the idea of a global schedule, needs to be reviewed. Given the differences in country-specific burden of diseases and health infrastructure, it seems unlikely that a single schedule could now be best for all countries.

Under the banner of the ‘Optimizing Immunization Schedules Project’, the WHO Initiative for Vaccine Research (IVR) is coordinating efforts to review the evidence and evaluate different vaccination schedules in different epidemiological and health care contexts, recognising that:

  1. it is likely that different schedules will be appropriate for different parts of the world; and
  2. review of the schedule will be an on-going process as new vaccines are introduced and as circumstances evolve.