How has the use of vaccinations changed over time?

The use of vaccinations has evolved significantly over time, from crude methods to sophisticated, targeted immunisation strategies.

In the early days, the concept of vaccination was quite rudimentary. The first known vaccine, developed by Edward Jenner in 1796, was for smallpox. Jenner discovered that milkmaids who had contracted cowpox did not get smallpox. He hypothesised that cowpox protected against smallpox, and tested this by injecting a boy with cowpox pus. The boy developed mild cowpox but did not get sick when later exposed to smallpox. This marked the birth of vaccinations.

Throughout the 19th and early 20th centuries, vaccines were developed for other diseases like rabies, diphtheria, and tetanus. However, these early vaccines often had severe side effects and were not always effective. The production was also not standardised, leading to variations in quality and effectiveness.

The mid-20th century saw significant advancements in vaccine development. The polio vaccine, developed by Jonas Salk in 1955, was a major breakthrough. It was the first vaccine made from 'killed' virus, which was safer than using live viruses. This paved the way for the development of other inactivated vaccines. Around the same time, Albert Sabin developed an oral polio vaccine using weakened virus, which was easier to administer and provided longer-lasting immunity.

In recent decades, the use of vaccinations has become more widespread and systematic. Vaccination programmes have been implemented globally, targeting various age groups and populations. The World Health Organisation's Expanded Programme on Immunisation, launched in 1974, has played a crucial role in increasing global immunisation coverage.

Technological advancements have also led to the development of more sophisticated vaccines. Recombinant DNA technology, for example, has allowed for the creation of vaccines against diseases like Hepatitis B and Human Papillomavirus. These vaccines are made by inserting a small piece of the pathogen's genetic material into another organism, which then produces an antigen that stimulates an immune response.

The use of vaccinations has also evolved in response to emerging health threats. The rapid development and global distribution of COVID-19 vaccines is a testament to this. Never before have vaccines been developed and deployed at such a scale and speed.

In summary, the use of vaccinations has changed dramatically over time, from simple inoculations to complex immunisation strategies. This evolution has been driven by scientific advancements, public health initiatives