Immunization, Vaccines and Biologicals

Optimizing immunization schedules

Building on the traditional EPI immunization schedule

The current basic paediatric vaccine schedule in use in many countries was established more than 25 years ago as part of the Expanded Programme on Immunization (EPI). Since the initial global vaccination schedule (6, 10 and 14 weeks for diphtheria-tetanus-pertussis-oral polio vaccine and 9 months for measles vaccine), the epidemiology of these infections has greatly changed. New vaccines have been designed and introduced, health services have changed and expanded, and other interventions have been linked to EPI activities (such as micronutrient supplementation and preventive treatment for malaria). In addition, much has been learnt about the mechanism of action and impact of all vaccines. In the context of these developments, and differences in country-specific burden of diseases, it is unlikely that a single, uniform immunisation schedule would now suit all countries.

Optimizing immunization schedules

Several epidemiological and modelling studies have explored the effect of specific vaccines on child health, but there has been little comprehensive evaluation of vaccination schedules at global or country level. The goal of the Optimizing Immunization Schedules project was thus initiated in 2010 to develop an appropriate process whereby decision-makers in low- and middle-income countries can determine optimal vaccination schedules. The ultimate outcome of the step-wise, consultative, web-based process is to reduce the burden of disease is a cost-effective manner.

This project is carrying out a systematic review of data on vaccination schedules for the following seven vaccines in terms of epidemiology, immunology, safety and logistic and programmatic issues:

  • pneumococcal conjugates (PCV)
  • rotavirus
  • diptheria-whole and acellular pertussis-tetanus (DPT)
  • hepatitis B (Hep B) and
  • Haemophilus influenzae type b (Hib) vaccines.

This process may identify critical gaps in evidence that hinder full evaluation and encourage a research agenda to answer key issues. The data collated will be inform an evidence-based decision-making approach that enables key stakeholders to design optimal vaccination schedules based on the local context and data.

Role of the Initiative for Vaccine Research

The project is executed by an ad hoc global multi-disciplinary network of experts in epidemiological and immunological methods, clinical trials, mathematical modelling and in each vaccine-preventable disease, under the leadership of the Initiative for Vaccine Research (IVR). Findings are presented to the WHO Expert Advisory Group of Experts on immunization (SAGE) to ensure that the outcomes of the project are appropriate and relevant to global immunization priorities.


Below are the links to available SAGE recommendations on the optimizing immunization schedules: