Vaccine

A modern kit to vaccinate against smallpox

James Gillray, The Cow-Pock—or—the Wonderful Effects of the New Inoculation! (1802). Vaccinations eventually helped eliminate smallpox from the world.

A vaccine is a medical intervention administered typically by healthcare professionals to confer immunity against specific infectious diseases caused by certain pathogens, including bacteria and viruses. Derived from living or once-living organisms, vaccines play a crucial role in preventing outbreaks of diseases and reducing the severity of illness in individuals. The term "vaccine" originates from the Latin "vaccīn-us", which is rooted in the word "vacca" (cow), a homage to the pioneering work of Edward Jenner with cowpox in the 18th century. The process of administering vaccines is termed vaccination.

History

The history of vaccines dates back to the 18th century with Edward Jenner's seminal work on smallpox. Smallpox was a lethal disease during this period. Jenner's observations led him to discover that individuals who had contracted cowpox, a disease related to smallpox, generally did not succumb to smallpox. To validate his hypothesis, Jenner administered cowpox to a young boy and subsequently exposed him to smallpox. The boy exhibited immunity to smallpox, confirming Jenner's theory that cowpox exposure provided protection against its deadlier counterpart.

By the 19th century, vaccination gained traction as a safer alternative to variolation, which was a direct inoculation with smallpox. In England, smallpox variolation was deemed illegal in 1840 due to the inherent risks. By 1853, legislation mandated smallpox vaccination for all children using Jenner's vaccine.

The progression of vaccine development saw significant milestones in the subsequent centuries. Louis Pasteur formulated a rabies vaccine in the 19th century. The 20th century witnessed the creation of multiple vaccines, including those against diphtheria, measles, mumps, and rubella. The 1950s marked another landmark with Jonas Salk's introduction of the polio vaccine. Despite these advancements, challenges remain, as vaccines for diseases like malaria and HIV are yet to be discovered.[1]

Various countries have implemented compulsory vaccination regulations, mandating vaccines for specific populations, primarily to ensure public health. Such laws often require children to receive particular vaccinations before entering public school systems.

Types of Vaccines

Vaccines are categorized based on their components and the method of preparation.[2]

Live vaccines contain a weakened form of the living pathogen, which induces an immune response without causing the disease. Examples include the vaccines for measles, mumps, and chickenpox. The immune system, upon exposure, "remembers" the pathogen, thereby providing protection against future infections.

Inactivated vaccines are formulated using dead pathogens. They generally elicit a less potent immune response than live vaccines, often necessitating "booster shots" to reinforce and prolong immunity. Pertussis (whooping cough), rabies, and hepatitis B vaccines fall into this category.

Additionally, advances in biotechnology allow for the synthetic production of certain vaccines in laboratories.

Two workers make openings in chicken eggs as they prepare to make measles vaccines

Effectiveness

Vaccines, while a powerful preventive tool, do not guarantee absolute protection against diseases.[3] Immunity might not be achieved for various reasons:

• Diminished immune system response due to existing conditions like diabetes, HIV, or old age.
• The body's inability to produce specific B cells for the requisite antibodies.
• Strain variations of a pathogen, wherein the vaccine targets a specific strain but not others.
• The transient nature of some vaccine-induced immunities, necessitating regular booster shots.
• Individual variations, including genetics, age, and ethnicity, can influence vaccine response. For instance, elderly individuals (typically aged 50-75 and above) might require larger doses due to diminished immune reactions.[5]

Controversy

Vaccination has encountered resistance and skepticism since its inception.[6] While the majority of the global medical and scientific community advocates for vaccination, citing its far-reaching benefits outweighing the rare adverse effects, some groups remain apprehensive. Critiques are often rooted in misinformation, fear, or personal beliefs. However, the consensus remains that forgoing vaccination poses significant risks, as vaccines have been instrumental in curtailing and preventing numerous infectious diseases, saving countless lives.[7][8]

See also

• Vaccine effectiveness

External links

• Vaccine - Citizendium

Vaccine Resources
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