Get Complete Information on Vaccines and Immune System

Immunity to a pathogen is not alike in every one. Various factors such as age, sex, nutrition, genetic back ground, and physiological status etc. influence imuune power.

It has been recognized for centuries that certain diseases never reappear in the same individual after recovery. Since immune system acquires defense mechanism in the presence of a pathogen, an individual recovered from a disease develops resistance to that specific disease causing agent.

Hence it is understood that resistance can be induced by the pathogen. Considering this fact, Chinese strived to prevent smallpox (a deadly disease characterized by pus filled blisters) by exposing uninfected individuals to substance of smallpox lesions.

The process was named as “variolation” from the root word “variola” a synonym for smallpox. Variolation – the age old practice of inoculation took a variety of forms.

One of it is removing pus and fluid from a smallpox lesion, and introducing it under the skin with a needle. Another method involved peeling scabs from lesions, drying and grinding them to a powder, and letting an uninfected person inhale this powder.

An alternate to this is picking up a small amount of the scab powder with a needle and introducing it directly into the veins. Lady Mary Wortley Montagu, wife of the British ambassador to Turkey, observed this third method and introduced this practice into England in 1721.

Although the effects of variolation varied, starting from mild illness in most individuals to death in a few, mortality and morbidity rates due to smallpox are certainly low in populations that used variolation than in those that did not.

In 1796 Edward Jenner, an English physician, used folk knowledge to find an alternative to variolation. He noticed dairy maids infected with cowpox are immune to small-pox. He then deliberately infected James Phipps, an eight year old boy, with cowpox and exposed him to smallpox virus.

The small pox virus failed to generate disease in Phipps. After repeating the experiment on other children, including his own son, Jenner concluded that cowpox infection provided immunity to smallpox without the risks of variolation. He published the conclusions of his experiment in 1798.

Consequently thousands of people protected themselves from the deadly smallpox disease by intentionally infecting themselves with cowpox. Jenner’s work became popular as “vaccination,” after “vacca,” – the Latin word for cow, and the substance used for inoculation is referred as “vaccine.”

Jenner in his experiment used a lancet to scratch some infected material from patient with cowpox and to introduce the same under the boy’s skin. Fifty years after Jenner, the hypodermic syringe became available.

In 1885, Louis Pasteur used one to vaccinate a young boy who had been bitten by a mad dog and was sure to die of rabies. The boy lived after immunization and immunization took another giant step forward.

Since then, technological improvements included safety features, sharper and thinner needles.

Even though, hypodermic injection remains the most common method of getting vaccine, it is not the only technology for immunization. Engineers and scientists continue to search for alternative routes such as mouth, nose etc. to introduce the vaccine.

The widespread vaccination technology has been marked a decrease in diseases, which once ravaged the world’s population. An example of this is smallpox, once it is a major cause for death world-wide.

Now the smallpox virus is found only in freezers, in high-containment laboratories the “Center for Disease Control and Prevention (CDC)” in Atlanta and the “Institute for Viral Preparations” in Moscow.

Vaccines are effective in preventing diseases, not only in individuals, but also in communities. This type of protection is called “herd immunity” or “community immunity.”

When a disease spreads from one individual to another, it requires both an infected individual to spread it and a susceptible individual to catch it. Herd immunity works by decreasing the numbers of susceptible people.

When the number of susceptible people drops low enough, the disease disappear from the community because of non availability of enough people to carry on the catch-and- infect cycle.

The greater the proportion of vaccinated members of a community, the faster the disease disappears. This is the reason that school children are often required to be vaccinated before attending school. Vaccination has resulted in marked decrease of many diseases including pertussis (whooping cough), polio, smallpox, and others.

Since vaccine tricks the body’s immune system to produce antibodies to fight with a specific pathogen before the entry of effective pathogen, the vaccinated person is able to eradicate the pathogen immediately after its entry in to the body.