Vaccination: the success over infectious diseases

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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 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 ( 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.


About Dr Mario Perro, PhD
The path for understanding reality

10 Responses to Vaccination: the success over infectious diseases

  1. Radhika Srinivasan says:

    Hi Mario! Well done for putting on this interesting and informative information on vaccinations. My friend has decided not to vaccinate her child which still perturbs me so I will forward her your blog to see what she has to say (at least she can’t say that you are being swayed by rich pharmaceutical companies!)

    • Well that’s true, I’m not really making science for money!
      I decided to write this post exactly for that reason: the vaccination is commonly considered dangerous and it took me a while to understand why. I’m not sure I found all the reasons of the origin of that fear, but I hope to contribute to the awareness on vaccine potential.

  2. stefi says:

    Hi guys,
    vaccination is something difficult to explain. Suppose that I don’t know anything about vaccination and you tell me to inject into my body an attenuated pathogens, maybe I will not completely agree. Now for some types of virus the vaccination is widely accepted, because it is well demonstrated that it is not dangerous, but for some others it is still controversial, at least in the public opinion. Let’s talk for example about the flu, it is really necessary to be vaccinated? And especially about the swine flu: I would like to ask you something more about the disputed swine flu vaccination. Why the vast majority of people decided not to get vaccinated against it, despite the spread of panic about the dangerousness of that flu?



    • Such important questions requires a long answer…
      Although in the past attenuated pathogens were used to induced immunity against certain diseases, today this is no more the case, at least for the newest vaccines that instead use only the proteins of the pathogen that are of course non-pathogenic. The allergic reaction you can have after vaccination can be probably comparable to that you can have by taking an antibiotic. Drinking alcohol or smoke a cigarette kill much more people than allergic reaction to vaccines.
      As the pathogens are different from each others, also the vaccines for different pathogens differ. For this reason all the new vaccines have to be tested and approved by WHO (and by the health department of each country) after examining the data provided by clinical studies. In the case of vaccines, the procedure can be speeded up if necessary just because the vaccine preparation is composed by coupound previosly used but with different pathogen protein, that unlikely change notably the bio-safety of the vaccine.
      As you can read in the “paper of the week” in the sidebar of the blog, WHO estimated that influenza virus causes “1 billion infections, 3 million to 5 million cases of severe disease, and between 300,000 and 500,000 deaths annually.” These numbers sounds like a good reason to develop and use vaccines.
      People didn’t get vaccination against the flu for several reasons (in my opinion):
      1) The main purpose of a Pharmaceutical company is to make profit and not treat people (that’s why they didn’t produce vaccination for third world countries). Vaccines, medicines are all services and goods they provide to make profit. Therefore, people look at them suspiciously especially when government imposes vaccination campaign, feared of economical interest and corruption behind it. However vaccination is still a potent weapon against infectious agents.
      2) Once out of Mexico, the swine flu stopped being so deadly in young healthy people and therefore wasn’t such a big risk being infected by it. The only people who died where persons affected also by other disease: for them Flu vaccines are very important. Those patients are forgotten by general public therefore nobody really cares about them, their death are considered normal circle of life. But if most of the population was vaccinated, also the weaker could survive.

      The only doubt I have is: there is a limit in the number of vaccines a human being can have? This question should get a scientific answer before starting in future multiple vaccination campaigns for any possible pathogen.

  3. zago says:

    Dr Mario,
    can we have some statistics about Vaccination Vs mortality reduction?
    Are there statistics about allergic reactions?


  4. Davide says:

    Interesting stuff in the last issue of STM (for those who have full access): Title is appropriately “A Crisis of Public Confidence in Vaccines” and Mario was precursor! Have a great one!

  5. Radhika Srinivasan says:

    Davide, do you have full access? Can you send me the article? cheers, Radhika

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