October 16, 2009
If you think that all problems are solved after you have read all about the long vaccine production, you’re wrong. There is still the issue of distribution:
As the vaccine manufacturing process is slow and continuous, it is not possible to produce enough doses for everyone. Nowadays, our yearly vaccine production is of 700 to 900 million at a maximum. In the case of an outbreak, changing the vaccine’s composition for a single extraction, as opposed to the three generally used, may imply a production two or three times larger, but still far from the necessary amount to immunize everyone. This may not even happen, considering that a single dose is enough for immunization. 
This scenario gets worse by the nature of a pandemic virus. Instead of the seasonal virus, which is already known and followed up during the year, the pandemic virus has never been seen before. We can produce and store vaccines against seasonal flu even if the virus mutates, the odds of crossed immunity (immunity against the vaccine that attacks the new virus) are high.
In the case of pandemic virus, the chances of having the right vaccine stored are very low. Influenza A (H1N1) is not recognized by antibodies generated against the latest seasonal vaccines, although it is susceptible to those generated against the 1976 vaccine. It makes sense, since the 1976 vaccine was produced against a swine virus. 
That is why we can not rely on previous vaccines and we need to speed up in order to develop a vaccine against Influenza A (H1N1), and the same goes for the next pandemic virus appearance. We can develop the vaccine’s strainn and start production only after the virus appears, following up closely its mutations to certify that the vaccine will still generate protective immunity.
With doses production in a continuous flow, governments need to prioritize who must get them first. Here, a point must be made. In the case of a serious outbreak caused by a quite lethal Influenza, as it would be the case if a highly pathogenic H5N1 was to be efficiently transmitted between humans, everyone would need to be immunized under risk of death. But in the case of a pandemic virus as Influenza A (H1N1), which its main threat currently is the amount of people it may infect and not its severity, the immunization objective is to reduce the chances of spreading the virus.
For the Influenza to spread and live within a population the number of susceptible people must be quite large and they need to be in very close contact with each other since a person who contracts flu gets cured in about a week, and later is immunized against that virus strain. The flu “disappears” after winter because a large amount of people is already immunized, and favorable conditions for the spreading of the virus are over. Vaccine’s role is to break that chain.
The vaccination priority is to guarantee that people that were exposed to risks have their health protected, as elders and health employees, and to undermine the virus transmission seedbeds. Hence it is important to immunize children at school age. They are instrumental to deter flu from spreading, at least according to the last transmission mathematical models. 
When a child that is going to interact with other children at school, parents or manipulate toys and get in touch with several objects and common spaces, is immunized the protection reaches not only the child but everyone around him. Imagine a housewife that gets a vaccine dose but is not supposed to get in touch with many people. She is a terminal point in the transmission chain, and only that point will be out of risk. When a child gets a dose, all points which will get in contact with the child will be more protected.
However, planning is not limited to distribution within one country. There is also the issue of granting poorer countries access to the vaccine. Flu’s vaccine is produced by few and huge private research centers, which charge for the doses. In the case of seasonal flu, demand for doses is quite lower than production-limit, once Influenza is not a big threat in many places, and the immunization focus are the most susceptible we have seen. But during an outbreak as we have now, all available doses are bought. The whole 2009 production is compromised.
How can poor countries have access to this, if in many places medicine costing dollar cents are not taken? Some laboratories have promised to distribute millions of doses for undeveloped nations, but the numbers are not even close to real necessity. The market rationale of giving more to those who pay more should not be applied to such an important topic as the protection against an outbreak. 
Finally, there is another delicate issue in immunization. Public’s acceptance. In addition of receiving and distributing vaccine doses as soon as possible, countries must ensure that their inhabitants will adhere to immunization. At this point, undeveloped countries are better prepared, for they are still preparing their large-scale immunization campaigns against a series of diseases which already have disappeared in richer nations.
Here, the role of making population conscious and clarifying questions is very important. Even more important since anti-immunization campaigns are getting stronger in the United States and are arising in Europe, as well as e-mails and websites that hold false information (that vaccine may kill or that it contains mercury, etc). We can not go through the whole process of producing, distributing and storing vaccines and fail at the last stage, which is to guarantee that all people in need of immunization are really immunized.
 Butler, D. (2009). Vaccine decisions loom for new flu strain Nature, 459 (7244), 144-145 DOI: 10.1038/459144a
 Hancock, K., Veguilla, V., Lu, X., Zhong, W., Butler, E., Sun, H., Liu, F., Dong, L., DeVos, J., Gargiullo, P., Brammer, T., Cox, N., Tumpey, T., & Katz, J. (2009). Cross-Reactive Antibody Responses to the 2009 Pandemic H1N1 Influenza Virus New England Journal of Medicine DOI: 10.1056/nejmoa0906453
 Medlock, J., & Galvani, A. (2009). Optimizing Influenza Vaccine Distribution Science, 325 (5948), 1705-1708 DOI: 10.1126/science.1175570
 Yamada, T. (2009). Poverty, Wealth, and Access to Pandemic Influenza Vaccines New England Journal of Medicine, 361 (12), 1129-1131 DOI: 10.1056/NEJMp0906972