Q&A Feature on Combination Vaccines
SPECIAL FEATURE WITH BIRGITTE GIERSING AND MATEUSZ HASSO-AGOPSOWICZ - WHO'S DEPARTMENT OF IMMUNIZATION, VACCINES & BIOLOGICALS.
- Why are combination vaccines so important for childhood immunization programmes globally, and what benefits do they offer to families, health workers and health systems?
Combination vaccines enable a greater number of vaccines to be administered to young children in a fewer number of injections and health visits. Reducing the number of injections administered during a single childhood visit can lessen stress for children and increase caregivers’ willingness to vaccinate and protect their children.
Combination vaccines also have advantages for immunization programmes because greater acceptance translates to increased coverage and protection from disease, which is accompanied by substantial health and economic benefits for populations. If multiple vaccines can be administered in a single shot, this substantially simplifies the logistics of vaccine delivery to the point of administration and potentially the overall cost to immunize a child.
How could additional combination vaccines in the future help address increasingly crowded immunization schedules and improve the delivery of childhood vaccination?
New combination vaccines could help to liberate ‘space’ within the existing immunization schedule for young children. Currently, WHO recommends 14 universal vaccines globally, and additional vaccines in specific regions, for example, where diseases such as malaria and dengue occur. When multiple vaccines are combined into one, a child only receives a single injection, while being protected from multiple diseases. This also creates an opportunity to administer other vaccines against severe diseases by liberating "space" in the immunization schedule.
Novel combination approaches are particularly critical to ensure that new vaccines that are currently in development will be introduced, because when a new vaccine is safely combined with an existing vaccine that is already in the schedule, this removes the need for an additional injection or visit. For some vaccines in development, combining them with existing vaccines will be essential to be able to introduce and use them effectively.
- What are the main challenges to developing, evaluating, manufacturing and introducing new combination vaccines?
Product development of any vaccine is costly, lengthy and high-risk, and this is compounded in the case of combination vaccines because of the need to develop multiple vaccines concurrently and demonstrate that they are safe and protect against deadly diseases. The vaccines to be combined must have compatible epidemiology, i.e., occur in the same geography and population, have similar schedules to offer protection before the peak age of risk, be technically feasible to manufacture and package together, have clear regulatory and policy pathways, and be of sufficient commercial interest for investment by developers.
A significant challenge lies in the uncertain market for novel combination vaccines. Currently, there is no mechanism to identify and signal the need or preference for novel combinations from policy-makers, and no market shaping strategies exist to de-risk investment in their development. Consequently, there are very few novel vaccine combinations in the pipeline.
- How are WHO and partners working to overcome these obstacles and facilitating the development and uptake of priority combination vaccines?
WHO and partners are seeking to de-risk product development in novel combination vaccines by identifying priorities for development and clarifying the pathways to approval, policy and financing.
WHO and PATH have been collaborating for the past 2 years to develop a systematic framework to identify the most programmatically important new combination vaccines for routine use in children under 5. Hundreds of potential combinations of both already licensed vaccines, and pipeline vaccines with licensed vaccines have been assessed for programmatic, technical and commercial feasibility, with input from regulators, developers, manufacturers, policy makers and immunization partners.
WHO established a technical advisory group of independent experts to help steer the approach and the process as the framework was developed. Through extensive consultation with National Immunization Technical Advisory Groups (NITAGs), including in low- and middle-income countries, a list of 15 priority new combination vaccines has been proposed.
- How could new combination vaccines help improve equitable access to vaccination, particularly for children in low-resource, remote or hard-to-reach settings?
In remote and hard-to-reach settings, there are generally fewer healthcare workers, limited healthcare facilities and severely constrained infrastructure for vaccine transportation and refrigerated storage. Novel combination vaccines need less space in the cold chain and require less time to prepare and administer, thereby increasing the feasibility of delivery by a healthcare worker.
The product attributes of combination vaccines enable greater and more equitable access to vaccination by easing delivery to the most challenging environments.
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Further information on WHO’s work on immunization is available here.