ISTANBUL — We took an exclusive interview with Dr. Peter R. Paradiso, head of vaccines department of Wyeth Pharmaceuticals, about vaccines, problems in vaccinations, solutions and new vaccines including Prevnar, a 7-valent pneumococcal conjugate vaccine.
On which criteria are vaccine development and production decisions based?
There are very important criteria about vaccines. The first of them is, of course, medical requirement. As may be clearly seen, the focus is on diseases which are vital for public health. As for the pneumococcal disease, the bacteria causing this disease is a factor leading to meningitis, bacteraemia and pneumonia in all ranges of age. It affects not only infants, but also adults and particularly elderly people. Pneumococcal infections have impacts on a substantial part of society with serious implications that lead to diseases required to be prevented. According to World Health Organization, it is the leading infectious disease causing infant mortality worldwide. This is a driving factor to make a decision for development of a pneumococcal vaccine. The second criterion is whether the vaccine is technically feasible and there is confidence for its success. As for the pneumococcus, there are past experiences gained with the similar, capsular bacteria. We had the basic opinion on how the vaccine against pneumococcus must be designed, since a successful result was in hand with haemophilus influenzae type b. On the other hand, the efforts to develop a vaccine against HIV were prevented by technical problems despite we had considerable knowledge of the disease. The third criterion is also related to medical requirement. The vaccines are usually developed against the diseases commonly encountered worldwide. It is not possible to develop a vaccine against a regional illness. And of course, the fourth one is that the vaccine to be produced should have a commercial value. For the producing company, profitability is important. To be honest, when there is a need in terms of public health, there is also a commercial value.
What are difficulties specific to development of pediatric vaccines?
The pediatric vaccines are intended for the most valuable and healthy portion of the society. The utmost care must be given when developing a vaccine for such a group. The vaccines being developed are tried initially on the adults and then on the older children and finally they are applied to the infants, as the ultimate target group. However, as the process is not finished yet, vaccine-related effects are followed up through comprehensive confidential databases. For the clinical trials related to Prevnar, some 40,000–50,000 infants were involved. These studies are very large-scale since both efficacy and safety data bases are created. But monitoring is continued also after licensing for safety issues. As far as Prevnar is concerned, data belonging to 150,000 children are monitored in a detailed manner. Many countries have their own vaccine survey system to record any unexpected effects post-vaccination. Prevnar has been vaccinated for more than 150 million doses up to now, and no safety problems have been observed.
You worked for leading organizations such as CDC and WHO. What kind of experience did you get, or what kind of lessons did you learned about a new vaccine?
We can mention different lessons learned for different groups of people. However, the most important problems for all groups are the process of taking the vaccine out of the refrigerator and injecting it to the infant and trying to ensure that everybody is vaccinated. Training is the major component for all stages: it is vital for the matters such as how the vaccine is to be stored and follow-up of who has been vaccinated and who has not. In developing countries, re-building of infrastructure may be required to be able to distribute a new vaccine, but in countries such as the U.S., a current system and capacity is already available to integrate a vaccine into. When a new vaccine is launched, some problems may arise as to whom the vaccine is to be distributed by, how the cold chain is to be maintained, etc. The same problems have been faced in the case of Prevnar as well. WHO asks that this vaccine is applied in every country worldwide. Delivery of the vaccine to WHO is only a little part of the job. Solutions to be offered to problems specific to each country are different.
In which countries is Prevnar integrated into the routine vaccination scheme?
Prevnar is currently integrated into national vaccination schemes of nearly 20 countries worldwide, including the U.S. and European countries. The number of countries having licensed the vaccine is 90. I think Turkey is one of the countries planning to include the vaccine in routine vaccination scheme.