They also contain additives, substances added in very small quantities, which are designed to prevent bacterial contamination, maintain the effectiveness of the vaccine over time and help stimulate the immune response.
The vaccines are first of all HARMLESS: they must not in fact provoke the pathology of which the corresponding virulent microbe is present in nature and must stimulate our immune system without making us sick.
They are obviously also EFFECTIVE: the vaccines must provoke an antibody response that is able to give resistance to the disease by the vaccinated subject for the longest time possible.
The safety of vaccines
Many vaccine disputes revolve around the definition of “safe vaccine”. If by this term we mean a product that is totally free from negative side effects, then no vaccine is 100% safe, just as no human activity is safe: a certain risk, however small, exists in all our activities. Even the environment perceived as safest, that is our home, involves a risk: it is estimated that in Italy every year more than 4,000 people die from domestic accidents. By “safe” we mean a vaccine which decreases the risk and increases the safety of not dying and of not getting sick for a vaccinated population and that only exceptionally can cause serious side effects. The risks are considered acceptable, precisely because a vaccine defends against a greater danger represented by the disease.
How do vaccines work?
The vaccines have the function of preparing our immune system against a specific opponent. To do so, however, they submit a much weaker version of the virus or bacterium than they would encounter in nature, so that they can easily defeat it and at the same time discover its “weaknesses”. This allows our body to react promptly in case of attack by these microorganisms, fighting them in the bud and avoiding the risks that we would run if contracting the disease.