Thank you to Dr. Omesh Kumar Bharti for posting this article. The news it reports has received a lot of media attention over the past few days, and in many media around the world.
While I personally believe that any progress towards more stable vaccines is great news and takes us in a very good direction I would like to make a few comments that may give some perspective to the "discovery" announced by the Oxford University
1) The first efforts to stabilize vaccines in sugar started in the late 1980's early 1990's. Financial constraints and then legal fights around sugar-glassification technology IP issues have prevented these discoveries from having any substantial impact so far .
2) Extensive work done on the issue of vaccine stabilization has been done by PATH (
www.path.org) . Since 2003, PATH has worked under funding from the Bill & Melinda Gates Foundation on a project to assess the technical and commercial feasibility of stabilizing vaccines for developing country immunization programs. Many of their recent publications can be found on our web-site at:
http://www.path.org/projects/vaccine-stabilization-news.php.- The head of this effort at PATH is ms Debra Kristensen [
[email protected]]
[email protected][/email]
3) Many vaccines are already quite heat stable
It is also important to note that many vaccines today on the market are already quite heat stable for extended period of time. The attached table shows that some vaccines can actually withstand a fair amount of heat exposure. However the range of vaccines that are commonly delivered by the Expanded Programme on Immunization (EPI) have very different heat stability profiles: the Oral Polio vaccine (OPV) being the most heat sensitive and Hepatitis B (HepB) and Tetanus Toxoid (TT) being the most heat stable (but also the most sensitive to freezing!!!)
One current route being explored in order to assist developing countries with the logistics constraints they face with their immunization programme and the cold chain , is to encourage manufacturers and regulators to reflect the true heat stability of the vaccines they license in the prescribing information of these products. This would allow, in many cases, the products to be used for a limited period of time (e.g. up to 30 days) in a higher temperature environment ( e.g. 30°C) . At the moment, unfortunately all products are simply licensed for use between 2 and 8 ° C no matter what their true stability is
4) Do we still need a cold chain?
The cold chain, with its simple and rather strict rules can be perceived as a burden for countries, however, beyond the need to have refrigerators in place through the country, the establishment of the "cold chain" has been a very powerful process to create what has actually become the "backbone" of immunization programmes, made of simple managerial rules as well as strong logistics and supply systems. The Cold Chain has made it possible for EPI to reach out to over 80% of the children under one year of age all over the world and achieve coverage rates higher than with any other public heath intervention.
While processes and formulation approaches do exist and new ones are being developed to improve the heat stability of vaccines, industry is in fact reluctant to apply these processes to existing, already licensed vaccines.
Indeed , the cost associated with the re-licensing of an existing product are such that they do not see the advantage (from a financial or market perspective) of going this route.
At the moment the public sector provides no incentive for industry to improve existing products. If such incentives could be put in place (e.g. the public sector could signal that they would accept to pay a higher price or guarantee a certain level of demand for more heat stable vaccines)) then perhaps we could see a change in the products being developed and licensed.
Even for new vaccines, the goal of industry is understandably to license and bring the product to the market as quickly as possible to start generating revenues. Additional efforts required to improve the heat stability of the product or even to carry out tests to document the true heat stability represent delays which cost money and for which no market incentive or compensation mechanism currently exist.
5) Can the Oxford University help transform immunization programmes ?
A new technology, like this one, can help trigger some changes and possibly contribute to more discussions around a possible new immunization paradigm;
However this technology is not perfect, the sugar-classification methods of stabilization result in dried products that must be reconstituted with a diluent before they are administered. So , if the need for refrigeration is removed, the technology introduces an additional constraint, the reconstitution step. There might be a way to design single-dose devices that perform the reconstitution in a self-contained manner which would improve ease-of-use and safety, but these are likely to be costly.
Furthermore, one technology alone will not be sufficient to transform immunization programmes. A range of new technologies will be required as well as a combination of other very critical factors which would constitute an environment that is conducive to the widespread adoption of the new products:
incentive structures put in place by the public sector to encourage a range of companies to move in this direction as there will need to avoid monopolistic situations which would not be good for the price of the products , the confirmation of the interest/ demand of recipient countries that will be using these products and the associated financing mechanism regulatory pathways need to reflect the true heat stability of vaccines in the prescribing information as long as some vaccines continue to require active refrigeration either permanently (oral polio vaccine for instance) or at least at the time they are reconstituted (Measles, Yellow Fever, BCG for instance) some cold form chain will continue to be needed Michel Zaffran
Senior Adviser WHO/IVB & Director, Project Optimize
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Optimize - Immunization Systems & Technologies for Tomorrow
A WHO-PATH Collaboration
Department of Immunization, Vaccines and Biologicals
World Health Organization
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