Vaccines are biological products made from living organisms. They have to be held to the highest standard of quality and safety.
At each step of the manufacturing process, extreme care –and strict precautions– are taken constantly. Production takes place in a controlled atmosphere and absolutely sterile conditions.
Manufacturing a vaccine is a complex process involving many different steps, and each step in the cycle is strictly monitored from start to finish.
Continuous control along the entire production chain ensures that raw materials, equipment and manufacturing processes – and, naturally, the finished products – are of the highest quality. More than 70% of the time required to produce a vaccine is spent on these controls.
Each and every batch of vaccine that is manufactured must undergo routine testing to ensure purity, efficacy, microbiological security and safety. There are no exceptions: if a batch does not meet the quality criteria, it will not be distributed. For some vaccines, more than 50 different tests may be carried out at various stages of production.
As the batches come out of production, samples are taken from each batch and sent to the health authorities. These samples undergo another series of tests. Only after the vaccines have successfully passed all these tests can distribution begin.
The total time required to produce a vaccine, if one includes all the controls and checks, ranges from 6 to 22 months! For example, 6 months for an influenza vaccine, and 22 months for a polio vaccine.
Once the vaccine has been identified (the best candidate vaccine selected), the longest and most complex phase of its development starts: clinical studies. The aim is to demonstrate the tolerance and efficacy of the vaccine in a highly demanding and non-negotiable regulatory environment.
Clinical trials take place worldwide, in accordance with the same requirements and standards.
A dossier summarizing all the information gathered on the vaccine is then submitted to the various countries' health authorities. Independent authorities evaluate the efficacy and tolerance of the vaccine and decide whether the product may be sold.
Immunity is a highly sophisticated defense system called the immune system, the role of which is to prevent pathogenic agents, such as viruses, bacteria, or parasites, from propagating in the organism.
There are two kinds of defense mechanisms.
A first, relatively simple, non-specific line of defense is formed by the barriers isolating our organism from the outside, such as skin, for example, which provides mechanical protection thanks to its callus layer, or mucus membranes, gastric acid, etc.
Specific immunity on the other hand is infinitely more complex. It identifies the foreign body, destroys it with cells (lymphocytes, macrophages, etc.) or chemical substances specifically directed against it (antibodies), saves the intruder's identity in its memory and, if the intruder subsequently reappears, neutralizes it.
This is the principle on which vaccination is based. Vaccinating means teaching the immune system to first identify and then neutralize the infectious agent threatening it. Vaccination consists in introducing into the organism an agent (bacterium, virus or molecule) that has been stripped of its pathogenicity (ability to make you ill) but has retained its immunogenicity (ability to elicit an immune response). Upon subsequent contact with the pathogenic agent, the body will be able to defend itself independently. Vaccines enable us to acquire immune protection without having suffer the disease and its potential consequences.
There are three broad categories of vaccine:
So vaccines are made using micro-organisms that have been either attenuated or inactivated, or fragments of micro-organisms, and other components to preserve their qualities over time.
The World Health Organization defines WHO prequalification as a regulatory step aimed at ensuring that the diagnostics, medicines and vaccines available for illnesses that weigh heavily on public health comply with international standards of quality, safety and efficacy and contribute to the optimal use of resources in the field of health and to improvement in the overall health situation.
The prequalification process, as defined by the WHO, consists of a transparent and robust scientific evaluation, which involves reviewing the dossier, performing analytical tests on lot-to-lot consistency and assessing performance, as well as on-site inspections of manufacturers. This information, together with other criteria concerning supply, is used by the United Nations and other agencies in making decisions on the purchase of diagnostics, medicines and vaccines.
WHO prequalification of a vaccine represents a crucial stage on its way to becoming generally accessible and used where it is most needed.
Vaccination is an act of individual protection. It is also an act of collective protection against some contagious diseases (that are transmitted from individual to individual). In fact, a vaccinated person protects himself and, in most cases, by preventing the disease from spreading, protects those around him.
When a high percentage of the population is vaccinated, it has what is called collective or herd immunity. This collective protection applies to individuals who have not received the vaccine, as those that have been vaccinated indirectly protect the vulnerable individuals who have not yet been able to benefit from vaccination.
Many transmissible diseases survive in the form of epidemic waves, owing to the lack of collective immunity in a given population.
The vaccine coverage necessary to obtain optimal herd immunity varies depending on the disease. For example, for smallpox, diphtheria, poliomyelitis, rubella and mumps, the coverage threshold required to attain collective immunity is 80-85%. For pertussis and measles it is 90-95%.
Some epidemic outbreaks can be linked directly to the decrease in vaccination rates. Recent examples include the diphtheria epidemic in Russia, which crossed the border and spread towards the Northern European countries in the 1990s (in the absence of diphtheria booster vaccines), and the various measles epidemics that have been making their way across Europe for the last ten years (the United Kingdom, Germany, Switzerland, etc.)
Answer: smallpox. The very first smallpox vaccine was invented in 1798, by a British physician, Edward Jenner. In 1967, when the disease still threatened 60% of the global population and caused the death of one in four patients, the World Health Organization launched a large-scale mass vaccination program. The World Health Organization announced the total eradication of the disease, the only one to date, in 1980.
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There are three main types of influenza virus: A, B and C. Cases of type C are much less common in humans than types A and B, which is why seasonal influenza vaccines contain only types A and B. The seasonal influenza virus is directed against the A and B virus types that were the most prevalent during the previous winter and that are thus likely to be present during the next winter. Each year, the vaccine contains two A virus strains and one B virus strain.
Each year, the World Health Organization Global Influenza Surveillance Network analyzes thousands of virus samples from around the world in order to identify the seasonal influenza strains that are most likely to pose a threat to human health in the coming season. Each year, the vaccine manufacturers create a new influenza vaccine based on these forecasts. There are two formulations: one for the northern and one for the southern hemisphere.
When you are vaccinated against seasonal influenza, you are not given a dose of last year’s vaccine, but a vaccine whose composition has been updated to match the strains of influenza viruses circulating this year and thus ensure the best possible protection.
Sanofi Pasteur's seasonal influenza vaccines are licensed and distributed in over 150 countries. More than two billion doses have been administered worldwide over the past 60 years.
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According to World Health Organization estimates, vaccination saves the lives of more than 3 million people worldwide each year and prevents millions of others from suffering from diseases and permanent disabilities.
However, more than 3 million people, including 1.4 million children under the age of 5, still die each year worldwide due to lack of access to vaccines. The most deadly of the vaccine-preventable infectious diseases are measles, Haemophilus influenzae type b (Hib), pertussis and neonatal tetanus.
With a concerted effort, it is possible to eliminate, or even eradicate, certain diseases:
Smallpox, which used to kill 5 million people worldwide each year, was eradicated in 1980 and is now virtually forgotten. To date, the global fight against poliomyelitis has saved 5 million people from paralysis (WHO, 2005).
As vaccination has virtually eliminated most infectious diseases, such as tetanus, poliomyelitis and diphtheria, from certain countries, it is possible to forget how dangerous they are.
The microbes (bacteria, viruses, toxins, parasites, etc.) responsible for these diseases still exist, however, and remain a threat to unprotected individuals, with the risk of an epidemic if the population is insufficiently vaccinated.
While the risk of contracting these diseases is low in certain countries, importation remains a possibility. Travelers can contract them and spread them when they return. Vaccination is therefore essential, given the frequency of international travel.
Lastly, getting vaccinated also protects others, in particular those that cannot be vaccinated for medical reasons.
Answer: in 1885
After successfully preventing diseases in animals, Louis Pasteur treated a young boy, Joseph Meister, who had been exposed to the rabies virus. The treatment saved his life.
This event marked the first vaccination and the first vaccine against rabies.
A vaccine is a biological product whose purpose is to protect the people who receive it.
To ensure its full efficacy, it must be stored at the right temperature of +2°C to +8°C. Vaccines are sensitive to heat as well as to freezing; they must not be kept in a freezer.
The cold chain must be respected every step of the way, encompassing production of the vaccine and all the successive storage and transportation phases, through to its moment of use.
Regardless of the destination of the vaccines or the mode of transport (plane, ship or truck), sanofi pasteur has taken numerous measures to guarantee the cold chain. In addition to insulated packaging and the use of cold source equipment, which are adjusted depending on whether the vaccines are headed for a hot or cold country, different temperature indicators and recorders are used throughout the trip. Control numbers are assigned in order to verify that the conditions have been respected at every stage.