• 17th Century: In the Ottoman Empire, a process called variolation was practiced, marking an early form of vaccination.[1,2] 
• 1717: Lady Mary Wortley Montagu, the wife of the British ambassador to the Ottoman Empire, observed variolation and was impressed by its effectiveness. She wrote letters to her friends in Europe, advocating for its adoption, which led to greater awareness and interest in the practice.[2] 
• 1796: Edward Jenner, an English physician, made a groundbreaking discovery by using the cowpox virus to inoculate a young boy named James Phipps. This method, which provided immunity to smallpox, marked the birth of modern vaccinology and laid the foundation for future vaccine development.[3] 
• 1870s-1880s: French scientist Louis Pasteur developed chicken cholera, anthrax, and rabies vaccines. He used a process called attenuation, which reduced the virulence of pathogens while keeping them live, making them safe for use in vaccines. [3] 
• 1937: Max Theiler, a South African virologist, weakened the yellow fever virus by passing it through mouse and chicken embryos. This process rendered the virus less capable of causing disease while still inducing protective immunity. Theiler's work resulted in a safe and effective yellow fever vaccine, which remains used today.[4] 
• 1955: American virologist Jonas Salk developed the first inactivated poliovirus vaccine, which used a killed virus to stimulate immunity. This vaccine played a crucial role in significantly reducing the incidence of polio, a devastating disease that caused paralysis and death worldwide.[3] 
• 1961: Albert Sabin, a Polish-American medical researcher, introduced a live attenuated oral poliovirus vaccine, which provided a more practical and effective immunization against polio. This oral vaccine became widely used and contributed to nearly eradicating polio globally. Other live attenuated vaccines followed, including those for measles (1963), mumps (1967), rubella (1969), varicella (1995), and rotavirus (2008).[3,4] 
• 1980: The World Health Organization declared smallpox eradicated following a successful global vaccination campaign, showcasing the power and potential of vaccines.[3] 
• 1986: The first genetically engineered vaccine for hepatitis B was developed. This vaccine used recombinant DNA technology, representing a significant advancement in vaccine technology and paving the way for the development of future vaccines.[3] 
• 2006: The first vaccine to prevent cervical cancer was developed by targeting the human papillomavirus (HPV). This vaccine provided a means to significantly reduce the incidence of cervical cancer, highlighting the expanding role of vaccines in preventing not only infectious diseases but also certain types of cancer.[3] 
• 2020: The rapid development and emergency approval of mRNA vaccines for COVID-19 by BioNTech/Pfizer and Moderna demonstrated unprecedented speed and collaboration in vaccine research. These vaccines used messenger RNA technology and played a critical role in combating the COVID-19 pandemic.[5] 

References 

1. 1. Flemming A. The origins of vaccination. Nature Research. Published online September 28, 2020.  
2. 2. Dinc G, Ulman YI. The introduction of variolation ‘A La Turca’ to the West by Lady Mary Montagu and Turkey’s contribution to this. Vaccine. 2007;25(21):4261-4265.  
3. 3. Alder R, Fallon LF Jr, Hessen MT. Immunization and vaccination. In: Magill’s Medical Guide (Online Edition). Salem Press; 2023. Accessed July 10, 2024.  
4. 4. Desmond A, Offit PA. On the Shoulders of Giants — From Jenner’s Cowpox to mRNA Covid Vaccines. New England Journal of Medicine. 2021;384(12):1081-1083.  
5. 5. Sheposh R. mRNA vaccines. In: Salem Press Encyclopedia of Health. Salem Press; 2023. Accessed July 10, 2024.