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Emma is three years old.
She lives in Europe and goes to nursery school.
She's protected against several infectious diseases.
Fanta is three days old. She lives in Africa and this is her first visit to the doctor.
Thanks to the immunization campaigns organized in her country, she will soon be protected.
Clara is eight years old and she lives in Central America.
Clara is at risk of catching dengue fever. Soon a vaccine will be available to protect her against this disease.
Thirty years from now when Emma, Fanta and Clara are adults,
their own children will be protected against still other diseases thanks to vaccines.
But for now that’s far from their minds.
With the exception of clean drinking water, no scientific progress or technical innovation
can rival with the impact of vaccines when it comes to fighting infectious diseases.
It's true! Vaccines protect lives every day.
Today we have vaccines that protect against 26 different diseases.
Around the globe, the lives of three million men, women and children are saved each year,
thanks to vaccines.
But how do vaccines work?
Regardless of whether they target viruses or bacteria, vaccines work by
stimulating the body's natural defenses.
The human body has an incredibly sophisticated defense system: the immune system.
It's an internal army, made up of millions of different kinds of solider-cells:
lymphocytes,
macrophages,
and specialized molecules such as antibodies.
This army has a very specific job to do: Locate and destroy any infectious agent
that enters the body.
The better the immune system knows the enemy, the better equipped it is to fight it.
This is the principle on which vaccination is based.
Vaccination is a matter teaching the immune system to identify the infectious agent,
in order to neutralize it.
It is also a matter of refreshing the immune system's memory, so that in the future
it will be able to recognize viruses and bacteria.
So the enemy is allowed to come inside in order to teach the body to defend itself.
Exactly,
but certain precautions are taken like disarming it. During vaccination a bacterium,
a virus or one of the substances they produce is injected into the body.
But first, they are weakened sufficiently so they will not be able to cause disease.
At the same time they must remain antigenic, which means they're still
able to induce a protective immune response.
There are three major categories of vaccines:
Live attenuated vaccines contain living micro-organisms that been attenuated,
or weakened.
The oral polio vaccine and the measles, rubella, mumps and yellow fever vaccines
all fall into this group.
Inactivated vaccines are made using micro-organisms that have been inactivated, or killed,
during the manufacturing process.
This category includes vaccines to prevent influenza and pertussis.
Thanks to genetic engineering, new technology enables scientists to design what are called
“recombinant” vaccines, such as the hepatitis B vaccine.
So, vaccines are made from micro-organisms?
In fact, they are made using micro-organisms that have been attenuated or inactivated,
or fragments of micro-organisms. They also contain substances so that they'll remain potent
and not change over time.
Exactly how are vaccines made?
Vaccines are biological products, which means they are made from living organisms.
This fact makes a huge difference in how they are manufactured.
Take safety for example. 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.
Anything that enters or exists the production area is carefully monitored:
Water and other fluids,
even the air in the room which is constantly checked to insure it's sterile.
To avoid any risk of contamination, production technicians wear high-protection clothing.
Gowning up is no easy task.
In fact, the production agents are specially trained for this.
Quality is the next essential ingredient.
Manufacturing a vaccine is a complex process involving many different steps,
and each step in the cycle is strictly controlled from start to finish.
Continuous monitoring along the entire production chain ensures that raw materials,
equipment,
and manufacturing processes,
and naturally the finished products are of the highest quality.
The total amount of time devoted to tests and controls is substantial.
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 fifty 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.
Considering that vaccines are going to be injected into a healthy body so many precautions are understandable.
I never imagined making a vaccine could be such a complex process.
It's also a very long process.
The total time required to produce a vaccine if one includes all the controls and checks
ranges from six to 22 months.
For example six months for an influenza vaccine and 22 months for a polio vaccine.
So how's the production organized?
Production starts with growing viruses or fermenting bacteria.
Very small quantities of these micro-organisms are caused to multiply in order to harvest
extremely large quantities.
From just a few cubic millimeters of solution, it is possible to produce enough viruses or bacteria
to develop millions of doses of vaccines.
Each micro-organism requires specific conditions to reproduce.
Bacteria multiply all by themselves but they need to be put in the right environment,
which is carefully monitored.
Viruses are different.
They need other living cells-host cells-to be able to reproduce.
The first step therefore consists of growing huge quantities of these cells and then adding
the virus so that it will be able to multiply.
Micro-organisms are grown in special complex growth media
that may contain up to thirty different ingredients.
A wide range of parameters must be taken into account:
Temperature
pH, oxygen rate,
sterility,
homogeneity, and so on.
Each factor is important.
The slightest variation in the culture media may compromise the results.
Depending on the vaccine, cell culture takes from two days to three months.
Following harvest, the next step is purification,
which eliminates any trace of culture media and any other impurities.
Inactivation takes place next.
This step is both extremely delicate and critical.
Inactivation consists of destroying the pathogens' ability to cause disease
while making sure they will still be able to induce an immune response.
At the end of this phase one obtains the very essence of any vaccine-its antigenic valence.
And it's this valence that protects the body.
Precisely!
When a vaccine confers protection against a single disease it is called a monovalent vaccine.
It is also possible for one vaccine to protect against several diseases
by combining several valences.
This involves great scientific and technological expertise. Each valence must remain fully effective
and yet it must not interfere with the other valences.
This careful, precise combination takes years of research to perfect.
Today it is possible to combine several valences to offer protection against
up to six different diseases with a single vaccine.
What happens once this antigenic valence is obtained?
Stabilizers and, in certain cases, a preservative are added.
The quantities are extremely small yet they are sufficient to guarantee that the vaccine will
remain stable, potent and effective.
Sometimes an adjuvant is also added to enhance the immune response.
The next step consists of filling syringes or vials with the vaccine.
Certain vaccines, such as the measles, rabies and yellow fever vaccines,
are not stable in liquid form.
They are put through an additional step to stabilize them.
Freeze drying removes moisture from the frozen vaccine under vacuum conditions and
at very low temperatures. The product is now a powder.
When it's time for the vaccine to be administered, it will be reconstituted by
combining this powder with a diluant.
When the filling phase is complete, each syringe and each vial undergoes routine inspection.
The quality of both the contents and the container are scrutinized.
For this phase of visual inspection, the human eye is aided by electronic cameras that detect
and identify even the smallest defect.
Final tests are performed by the vaccine manufacturer and then again by the health authorities.
The vaccines are then packaged and ready for shipping.
Once again, certain precautions are absolutely necessary.
From the moment the syringes and vials are filled up to the time the vaccines are administered to patients,
maintaining the cold chain is of the utmost importance.
Vaccines are fragile biological products and their potency can be lost if
they're exposed to light or to temperatures that are too warm or too cold.
To guarantee that vaccines will offer protection against disease, they must be stored at a constant temperature
between two degrees celsius and eight degrees celsius. Cold rooms, refrigerators,
and iso-thermal packaging ensure that they will be protected during each phase of
transportation and storage.
A monitoring device is included in each shipment to ensure the temperature is maintained throughout.
Even the slightest variation in temperature is indicated.
Now I understand why manufacturing vaccines is such challenging job.
It is challenging, yes. But, it is also very exciting.
At the end of the vaccine production cycle, the lives of millions of people are protected
against many different diseases, some of them fatal.
Today we have vaccines that offer protection against 26 different diseases,
such as tetanus
tuberculosis, polio and rabies.
Tomorrow, we will be able to fight other diseases,
ones for which a vaccine has not yet been developed such as dengue fever,
hospital acquired infections, and perhaps one day malaria and AIDS.
Vaccination is one of the most innovative fields of medical research,
and it has many more fascinating developments in store for us.