Vaccines - Introduction, Origin, Timeline, Types, Development, Table and relation with the economy

Know more about the need for immunization, history of vaccines, important vaccinations, reaction of vaccines etc



The vaccine (from the Latin vaccinus-a-um, 'cattle'; of Vacca-ae, 'cow') is a preparation of antigens that once inside the body causes an attack, called antibody. This response generates immunological memory resulting, in most cases, permanent immunity against the disease. The first vaccine was discovered that used to fight smallpox by Edward Jenner in 1796.

Vaccines are classified into two main groups

• Live vaccines or attenuated
• Killed or inactivated vaccines

Several methods of production:

1. Vaccines are prepared from avirulent forms of dangerous pathogenic microorganism.
2. Vaccines are prepared from dead or inactive.
3. Purified antigens.
4. Genetic vaccines.

The vaccines are administered through an injection, or orally (both with liquid and tablet).

Origin of vaccines

The smallpox was the first disease that man tried to prevent inoculated himself with another type of disease. It is believed that inoculation was born in India or in China around 200 BC In China, patients suffering from mild forms of smallpox pustules were collected fragments of dry grinding to obtain a powder-like mixture that is then introduced through the nose, hoping that this will immunize. In 1718, Lady Mary Wortley Montague reported that the Turks had a habit of also inoculated with fluid taken from mild cases of smallpox. Lady Montague inoculated her own children that way.

In 1796, during the peak extension of the smallpox virus into Europe, a country doctor in England, Edward Jenner observed that milk collectors occasionally bought a kind of "cow pox" or "smallpox vaccine (cowpox) for continued contact with these animals, which were then protected from smallpox common ill. Indeed it has been found that the smallpox vaccine is a mild variant of the deadly smallpox, 'human'. Working on this case, inoculation, smallpox vaccine, Jenner took the hand of Sarah Nelmes farmer. It was inserted through the fluid injection into the arm of an eight year old boy, James Phipps for the small symptoms of the infection of smallpox vaccine. Forty-eight days later, after which Phipps had completely recovered from the disease, Dr. Jenner injected the child human smallpox infection, but this time showed no sign or symptom of illness.

In 1881 takes place Louis Pasteur and his bold experiment brilliantly public verification of the effectiveness of the vaccine antiantraxic designed by him on the farm, now historical, of Pouilly-le-Fort. The development of the experiment was as follows: "On May 5 injected 24 sheep, 6 cows and 1 goat with 58 drops of a diluted culture of Bacillus anthracis. On May 17, these animals were inoculated again with the same amount of a crop less acute, or more virulent. On May 31 was the supreme test. were injected with a highly virulent cultures, all vaccinated animals and, in addition, 24 sheep, 1 goat and 4 non-vaccinated cows, which served as a control group testing. In June 2, select a well attended and appreciated the results, which were as follows: All the vaccinated sheep were good. Of the non-vaccinated, 21 had already died, 2 more died during the exhibition itself and the competition finally falling in the afternoon of that day. In cows, 6 were vaccinated, while the 4 unvaccinated showing all the symptoms of the disease and a febrile reaction. “In communicating these results, Pasteur introduced the terms vaccine and vaccination from the Latin word Vacca, resulting in the results obtained from inoculating the vaccine virus (cow-pox), in medical terminology as a tribute to Jenner, his illustrious predecessor.

Timeline of vaccines

Only smallpox has been eradicated in the world. The polio and measles are in eradication campaigns.

Eighteenth century

• 1796: First vaccine for smallpox.

Nineteenth Century

• 1879: First vaccine for severe intestinal chronic diarrhea;
• 1881: First vaccine for Anthrax;
• 1882: First vaccine for rabies;
• 1890: First vaccine for tetanus;
• 1890: First vaccine for diphtheria;
• 1897: First vaccine for plague.

Twentieth Century

• 1926: First vaccine for pertussis;
• 1927: First vaccine for tuberculosis;
• 1937: First vaccine for yellow fever;
• 1937: First vaccine for typhus;
• 1945: First vaccine for influenza;
• 1952: First vaccine for polio;
• 1954: First vaccine for Japanese encephalitis;
• 1962: First oral vaccine for polio;
• 1964: First vaccine for measles;
• 1967: First vaccine for mumps;
• 1970: First vaccine for rubella;
• 1974: First vaccine for chicken pox;
• 1977: First vaccine for pneumonia (Streptococcus pneumoniae);
• 1978: First vaccine for meningitis (Neisseria meningitidis);
• 1981: First vaccine for hepatitis B;
• 1985: First vaccine for haemophilus influenzae type b (HiB);
• 1992: First vaccine for hepatitis A;
• 1998: First vaccine for Lyme disease;

Twenty-first century

• 2005: First vaccine for human papilloma virus (the main risk factor for cervical cancer)
• 2008: The first vaccine to prevent addiction to heroin and cocaine (Although still making experiments with this vaccine to test its effectiveness)
• 2009: Vaccination against human influenza

Types of vaccines

The vaccines may be composed of bacteria or virus, whether live or weakened, they have been bred for this purpose. The vaccines may also contain inactive organisms or products purified from those first. There are four traditional types of vaccines:

Inactivated: harmful microorganisms that have been treated with chemicals or heat and have lost their danger. Examples of this type are: influenza, cholera, bubonic plague and hepatitis A. Most of these vaccines are often incomplete or of limited duration, so it is necessary more than one shot.

Live attenuated: microorganisms that have been grown specifically under conditions in which they lose their harmful properties. Often lead to a more durable immune response and are the most common in adults. For example: yellow fever, measles or rubella (also called German measles) and mumps.

Toxoid: these are inactivated toxic components from microorganisms, in cases where these components are the real cause disease, instead of the microorganism. This group may find the tetanus and diphtheria.

Subunitarias: rather than introduce an attenuated or inactive microorganism within an entire immune system, a portion of this can create an immune response. A typical example is the vaccine against hepatitis B subunitaria, which is composed solely by the virus surface (surface formed by proteins).

The vaccine against tuberculosis for example, is a vaccine called BCG (Bacillus Calmette and Guerin, who was named after its discoverers) is made with live attenuated bacilli and is not contagious disease.

Today we are developing and testing new types of vaccines:

Conjugate: certain bacteria have outer layers of polysaccharides that are minimally immune. Contacting the outer layers of protein, the immune system may be able to recognize the polysaccharide as an antigen (an antigen may be a protein or a polysaccharide). This process is used in the vaccine Haemophilus influenzae type B (also known as Pfeiffer bacillus).

Recombinant vector: combining physiology (body) of a given organism and DNA (content) from another, immunity can be created against diseases that have complex processes of infection.

DNA vaccines: recent developments vaccine is created from the DNA of an infectious agent. It works by inserting DNA from bacteria or viruses into human cells or animals. Some cells of the immune system recognizes the protein arising from foreign DNA and attack both the protein itself to the affected cells. Because these cells live long, if the pathogen (which creates the infection) that normally produces such protein is found after a long period, will be instantly attacked by the immune system. An advantage of DNA vaccines is that they are very easy to produce and store. Although in 2006 this type of vaccine is still experimental, it presents results.

It is important to clarify that, while most vaccines are created using components inactivated or attenuated micro-organisms, synthetic vaccines are composed partially or completely peptides, carbohydrates or antigens. These synthetic often considered safer than the former.

Development of immunity

The immune system recognizes the vaccine agents as foreign, destroying them and 'reminding'. When a really damaging version of the infection reaches the body, the immune system is already prepared to respond:

1. neutralize the infectious agent before it can enter the body's cells, and

2. recognize and destroy cells that have been infected before the agent can multiply in large numbers.

Vaccines have contributed to the eradication of smallpox, one of the most contagious and deadly disease that has known. Others such as rubella, polio, the measles, the mumps, the varicella-zoster (the virus that can cause chickenpox and the common herpes zoster) and typhoid fever are as common as a century ago. Since the vast majority of people are vaccinated, it is very difficult for an emerging outbreak and spread easily. This phenomenon is known as "herd immunity." Polio, which is transmitted only between humans, has been the target of an extensive eradication campaign that has seen limited polio endemic, being reduced to certain parts of four countries (India, Nigeria, Pakistan and Afghanistan). The difficulty of getting the vaccine for children has meant that the date of eradication has been extended until today.

Table of vaccinations

Aiming to provide the best protection, it is recommended that children be vaccinated as soon as your immune system is able to respond to vaccination, with subsequent additional doses as needed. Some vaccines are inserted several times not to make an assault on the agency's child once. With this objective is to develop the national vaccination schedules or tables.

Regardless of the immunization schedule and situations of travel, some vaccines are recommended throughout life (dose of remembrance) as tetanus, influenza, pneumonia, etc.. Pregnant women are often examined for their resistance to rubella. In 2006 has become a common vaccine against herpes zoster (shingles). For older people especially recommended vaccinations against pneumonia and influenza, diseases from a certain age are even more dangerous.

Vaccines and economy

The economy is one of the biggest challenges of vaccines. Many of the diseases that require a vaccine (including AIDS, the malaria and tuberculosis) are present especially in poor countries. Although some pharmaceutical companies and biotechnology have spurred the development of vaccines for these diseases do (given that expectations are low income) the number of vaccines actually administered has risen dramatically in recent decades, especially those fed to children in the early years of life. This may be due more to government than to economic incentives. Most vaccine development to date has been due to pulses of governments and NGOs, international agencies, universities...

Many researchers and politicians call to unite and motivate the industry, using mechanisms such as pricing pressures, tax or business commitments that can ensure that companies pay to achieve a successful vaccine against HIV (which causes AIDS).

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