Vaccination strategies:
how clinical trials are changing the game


Vaccines are one of the most effective methods of controlling infectious diseases. In an ever-changing world that is becoming increasingly interdependent, vaccination strategies need to respond to a wide range of climatic, economic, sanitary and political specificities. Challenges include developing health care systems worldwide, overcoming structural obstacles to the administration of vaccines, and improving monitoring, prevention, care and cooperation on a world scale.


Ensuring effective access to vaccination for as many populations as possible has become a priority, as exemplified by the rapid spread of Ebola since 2013, or the most recent outbreak of Zika. Today more than ever before, developing the appropriate technologies calls for changes in approaches to ensure this access to vaccination.


Vaccination strategies generally seek to achieve three main objectives:

- Preventing epidemics

- Limiting the spread of pandemics (epidemics that have already spread through human populations across a large region)

- Monitor and eradicate, when possible, infectious diseases through populations’ vaccination.


The implementation of improved, more flexible and better-coordinated vaccination strategies therefore calls for a holistic approach –encompassing not only the development of new vaccines and technologies, but also the development of vaccination infrastructures and programs.



Clinical trials are critical when it comes to defining the most effective and suitable vaccination strategies


Clinical trials not only test the safety and efficiency of new vaccines, they also disseminate valuable information on populations’ specific reactions and needs. Clinical tests, when implemented on a large scale, allow scientists and authorities to empirically identify the most efficient and adapted strategies.


Modern clinical trials seem to have incorporated lessons of the past: large scale tests developed in the 1970s showed for example that vaccinations extended to the entire population were only economically justified when associated with a very high guarantee of efficiency, a minimal single cost (< 0.5 USD), a wide popular approval of the vaccine, and a significant pandemic threat.


In developing countries, routine immunization campaigns –consisting of vaccines recommended by the World Health Organization’s Expanded Program on Immunization (EPI)- can be hindered by insufficient local health infrastructures.


In order to respond to the many economic, political and sanitary challenges associated with developing and administrating a vaccine, conception strategies now seek to incorporate larger pools of individuals and test as many products, timelines and infrastructures as possible.


In France, the Inserm institute is working on developing a large scale clinical trial to identify a therapeutic vaccine for Ebola through the EBOVAC2 project, in collaboration with African countries, the US and the European Union. The vaccine consists in a two-step process that includes a “prime” and a “boost”; the project aims to determine the most effective time lap to be adopted in-between the two shots.


While early trials have shown positive outcomes in terms of efficiency and security, the sustainability of such a solution will undoubtedly rely on the implementation of strict policies and sophisticated protocols worldwide.


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