By Mark DaCosta- Vaccines are critical tools in preventing and controlling infectious diseases by stimulating the immune system to recognise and combat pathogens – germs that can cause disease. In this three-part educational series of articles, how vaccines revolutionised medical science will be examined. This article – Part I – offers an overview of the world-changing concept. Part II will explore specific cases where vaccines have eliminated or mitigated diseases. Finally, Part III will discuss the cutting edge idea of mRNA vaccine technology.
According to historical records, the concept of immunisation dates back to ancient civilisations, where they practiced exposing individuals to smallpox scabs to induce artificial or acquired immunity. However, the modern era of vaccines began and took off in the late 18th century with Edward Jenner’s development of the smallpox vaccine, using cowpox to confer protection. Jenner had discovered that exposure to the less dangerous cowpox can make a person immune to the deadly smallpox. This development introduced a revolution in medicine — the vaccines revolution.
There are various types of vaccines, each designed to elicit an immune response against specific pathogens. Inactivated or live attenuated or weakened vaccines use whole viruses or bacteria that are either killed or weakened to stimulate an immune response without causing disease. Subunit, recombinant, and conjugate vaccines are those that focus on specific components of pathogens, such as proteins or sugars, to trigger an immune response. mRNA vaccines, a cutting-edge development, represent a newer approach that utilises genetic material to instruct cells to produce viral or bacterial proteins, training the immune system to recognise and respond to the pathogen, thereby preventing or mitigating the severity of the infection.
Vaccines work by mimicking an infection without causing illness. When administered, they prompt the immune system to produce antibodies and memory cells – cells that remember the pathogen and can destroy it. To be clear, antibodies are proteins that recognise and neutralise pathogens, while memory cells “remember” the pathogen, providing long-term protection. If the vaccinated individual encounters the actual pathogen later, their immune system can mount a rapid and effective response.
The history of vaccines is marked by significant successes, such as the eradication of smallpox in 1980 and the near-elimination of polio. This will be further examined in Part – II. Vaccines have played a pivotal role in reducing the global burden of diseases like measles, mumps, rubella, and influenza. However, challenges remain. Those challenges include vaccine hesitancy – as is observed in the COVID-19 pandemic, in which conspiracy theories emerged. Another challenge is the need for continuous development to combat emerging infectious variants of diseases. We have also seen this with COVID-19.
The groundbreaking mRNA vaccines, like those developed for COVID-19, represent a revolutionary leap in vaccine technology. Instead of using weakened or inactivated pathogens, mRNA vaccines deliver genetic instructions that instruct cells to produce a specific viral protein, triggering an immune response. This approach allows for rapid vaccine development and potential adaptability to emerging variants. This remarkable technology will be explored in Part – III
