Vaccination: the success over infectious diseases

Image via Wikipedia

As I mentioned in “The idea behind Educere X” , studying science helps to demolished wrong prejudices that negatively impact on human life. Today I want to demolish the prejudice against Vaccination and to demonstrate instead that vaccines are one of the main cause for improvement of world health.

Historically, vaccination has been seen as an invasive treatment associated with subsequently pains and in some cases the transmission of the disease it was aimed to protect from. In addition, most of the vaccination campaigns were imposed by governments that can be easily corrupted by the giant pharmaceutical companies, which look for increasing their business. These elements may explain why vaccines are still considered suspiciously nowadays, although vaccination has reached such impressive results (like eliminating the small pox virus as a epidemic pathogen) and many incredible advances has been achieved in vaccine design and safety. The concern for vaccines is also expressed by many blog where they describe a conspiracy for reducing world population. So let’s apply the scientific method to answer the question:

Are the vaccines useful for human health and survival?

• We can split the question above in 2 easier questions: Are the vaccines able to protect against pathogens?

Here I report a typical experiment performed in mouse model to determined that vaccination protect from disease caused by a pathogens:

The experiment is performed in parallel by treating a mouse with a vaccine consisting of attenuated pathogens emulsionated into adjuvant (that help to stimulate the immune response) and a mouse treated only with emulsionated adjuvant in a physiologic solution. If later (a month or so) the mice are infected by the living pathogens, the vaccinated one will remain completely healthy while the non-vaccinated one will develop the symptoms of the disease. This evidence is further sustained by the mechanistic correlation between protection and the systemic antibody level as shown by the plot on the right. It is easy to observe that while non-vaccinated mouse does not produce any antibody against the pathogen, the vaccinated one has a pick of antibody production some days after vaccination (usually around 7 days). The antibody level drops after pathogen clearing but didn’t go back to zero. The residual amount of antibody in mouse system (indicating the presence of long- living lymphocyte B memory cells that produce antibody) represents the “memory” of the immune system that is able to promptly protect against an infection of the same pathogen keeping healthy the vaccinated mouse. This process occurring during a vaccination can be repeated many times obtaining always the same result: protection of vaccinated mouse from the pathogens.

• Is this true also for human being?

That’s is definitely the case. The biggest success of vaccination is the world eradication of the smallpox virus. After being firstly described by Edward Jenner in 1796 with an unethical experiment on a 8 years old boy (a kind of experiment as shown above), the smallpox vaccines protect millions of people in Europe. As described in the 1996 annual report, a project of the World Health Organization (WHO) aimed to use the vaccination to prevent the 10-15 million people per year getting sick with 2 million people per year dieing in the poor countries. After 10 year of vaccination the small pox was eradicated from hearth. Nobody is infected by small pox anymore, since 30 years (1980 is the official declaration of smallpox eradication http://globalhealthchronicles.org/smallpox). They also proof the economical convenience of the vaccination campaign: they spent 313 million $ that have been largely repaid by saving on international surveillance activity and medical treatments, without considering the invaluable saving in human life.

Strengthened by this success, the WHO is now aiming to eradicates many other diseases of the third word countries by vaccinations: typhoid diarrhea, diarrheal disease caused by rotavirus, Streptococcus pneumoniae, Haemophilus influenzae and others. The GAVI association (http://www.gavialliance.org/index.php) strongly contribute in fund rising.

However new infectious disease are becoming predominant as killing agent such as West Nile virus, Dengue Virus and some old infection agent are still predominant such as malaria and AIDS because of lack in efficient treatments.

The research community is challenged to find treatment for these diseases. To reach this aim, money shouldn’t be the priority of government and pharmaceutical companies that deliberately don’t invest in this kind of research because the poor countries cannot buy the vaccines.

Related Articles

• Immune Response from Start to Finish: Part 3 [We Beasties] (scienceblogs.com)