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There has been a lot of controversy around the vaccination topic because parents are relying on inaccurate information to decide whether to vaccinate their children or not. Far from condemning this, our duty as scientists is to inform parents on how vaccines work, how they are developed and the regulations that exist to ensure their efficacy and safety.
From the lab to the counter
The main purpose of a vaccine is to protect us from developing a viral or bacterial disease. How? By letting our immune system recognize the virus or bacterium that causes the disease, so that it can produce defenses against it, in case of future infections.
Because exposure to the full bacteria or virus will certainly mean developing the disease, scientists came up with techniques that allow the inactivation or attenuation of the bacterium or the virus. This means that vaccines can contain these pathogenic entities in an inactive or non-disease causing state, or that their ability to cause disease is drastically reduced or weakened.
Inactivated and attenuated vaccines contain the entire bacteria or viral particles, but there are also vaccines that only contain parts of them, known as antigens, which are the fragments that actually participate in the activation of the immune system. These vaccines are known as fractional vaccines.
Testing the vaccines
Before a pharmaceutical company is allowed to produce and sell a certain vaccine, it has to go through several stages of clinical trials, in order to determine the effectiveness and safety of the vaccine in humans.
The pre-clinical development involves the research done in the lab, which includes the discovery of the antigens that could be potentially used to formulate a vaccine, and the experiments performed on cells or animals, to establish the efficacy of the vaccine.
The clinical development is the stage where the vaccine is first tested in humans. Clinical development is divided into four sub-stages, which last several years in total, depending on the results of each one of them. The first three stages are performed on volunteers and scale up in the number of patients as the vaccine goes from one stage to another. The fourth stage or “post-marketing surveillance” starts after the vaccine is introduced to the market, and its main objective is to detect any side effects related to the vaccine and to evaluate long term characteristics of it, including its efficacy.
In the U.S., the Food and Drug Administration (FDA) is the organism in charge of evaluating new drugs and vaccines and approve their production for their use in humans.