Community – Immunity

History

The first inoculation against the smallpox was observed over 2000 years ago in China and India by having children inhale the powders made from the skin lesions of patients recovering from the disease. However, a British physician Edward Jenner, is generally credited with the most dramatic succesful vaccination against the smallpox ever recorded. He utilized the the matter from the cowpox pustules to to beat the smallpox released by a related virus.

During the twentiteth century, there were developed several other vaccines, aiming protection against commonly fatal infections, such as diphteria, tetanus, polio and several others. In 1974, the World Health Organization (WHO), launched the Expanded Programme on Immunization with the goal to make sure that every child will receive the protection against six childhood diseases (tuberculosis, diphteria, polio, pertussis, tetanus and measles).

In 1999, the Global Alliance for Vaccines and Immunization was created to extend the reach of EPI, helping the poor countries figthing against diseases and introducing the vaccines into their national programmes.

Despite the fact that around 24 million of iinfants are still not receivnig the full EPI vaccines, the goal of the EPI programme is considered to be quite succesful, taking into consideration the reduction and even complete elimination of particular diseases.

How vaccines work?

In order to understand how the vaccine works, it is firstly necessary to understand the way immune system protects our body. Its purpose is to identify and destroy pathogens and neutralize the toxins produced by some bacteria.

The primary goal of all vaccines is to elict the immune response against antigen resulting in much stronger secondary response, when being exposed to the same antigen again. Vaccines actually encompass the same antigen found on pathogens associated with particular disease with the difference that exposure to the antigens is controlled. When vaccinated individual is exposed to the live pathogens in the environment, the immune system can destroy them before they can cause disease.

Natural infection and vaccination represent two ways of acquiring immunity. Their final result – immunity is fairly similar, but comparing with natural infection, vaccines do not endure the illness and eventual life – threatening complications.

Frequency and severity of adverse effects

Vaccinces should completely prevent the targeted ifection without adverse effects. However, this is not always the case. One of the keys, therefore, is to minimize those side effects as much as possible, which are, to some extent, expected to occur with a certain frequency.

Common and usually minor reactions, as a part of the immune response, include fever and malaise, whereas rare and more severe reactions are vaccine specific reactions, such as BCG osteitis and severe allergic reaction such as anaphylaxis.

Balancing efficacy and safety

Vaccine efficacy refers to the ability of a vaccine to bring about the intended beneficial effects on vaccinated individuals in a defined population under ideal conditions of use. The potential benefits of an effective vaccine – e.g. promotion
of health and well-being, and protection from illness and its physical, psychological and socioeconomic consequences – must be weighed against the potential risk of an adverse event following immunization (AEFI) with that vaccine. Vaccine- associated risk is the probability of an adverse or unwanted outcome occurring, and the severity of the resulting harm to the health of vaccinated individuals in a defined population following immunization with a vaccine under ideal conditionsof use.

For the full article click here.