The Oxford vaccine, Pfizer/BioNTech vaccine, Moderna vaccine, Covaxin by Bharat Biotech - these are words we are hearing everyday as the world anxiously waits for these vaccines as protection against the contagious Covid-19 virus that has wreaked havoc in our lives.
Even before, vaccines have helped the world eradicate deadly diseases like Smallpox and Polio. In 1979, the World Health Assembly officially declared Smallpox eradicated, a feat that remains one of history's greatest public health triumphs.
In more modern times, viral tissue culture methods led to the vaccine for Polio, a disease that has caused paralysis in millions of children worldwide. Government-led mass immunisation programs have now eradicated the disease from many countries around the world including India.
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But there was a time when the world did not know any vaccines.
How Jenner’s cowpox made history
A British physician, Dr Edward Jenner is considered the founder of vaccinology when in 1796, he inoculated a 13 year-old-boy with vaccinia virus (cowpox) and found immunity to Smallpox. That’s how ‘vaccine’ got its name. And the practice of intentionally exposing someone to trigger a mild, protective response to a dangerous disease, came to be called inoculation.
However, the history of vaccines did not begin with Jenner.
According to the Auckland-based Immunisation Advisory Centre, the practice of immunisation dates back hundreds of years. Buddhist monks drank snake venom to gain immunity to snake bite. Even the Chinese practised variolation or inoculation as early as 1000 CE. It was also practised in Africa and Turkey, and later spread to Europe and the Americas.
According to The Historical Medical Library of The College of Physicians of Philadelphia, the Chinese may have practised inoculation by scratching matter from a smallpox sore into a healthy person's arm.
Glynn and Glynn, in their co-authored book, The Life and Death of Smallpox, wrote that in the late 1600s, Emperor K'ang Hsi, who had survived smallpox as a child, had his children inoculated by grinding up smallpox scabs and blowing the powder into their nostrils.
The first lab vaccine
Though he is more known for his Pasteurisation process, a lesser known fact is that Louis Pasteur produced the first laboratory-developed vaccine in 1879: the vaccine for chicken cholera (Pasteurella multocida).
According to The History of Vaccines, Pasteur happened upon the method of attenuation by accident. In his lab, he was studying fowl cholera by injecting chickens with the live bacteria and recording the fatal progression of the illness. He had instructed an assistant to inject the chickens with a fresh culture of the bacteria before a holiday. The assistant, however, forgot. When the assistant returned a month later, he carried out Pasteur’s wishes. The chickens, while showing mild signs of the disease, survived. When they were healthy again, Pasteur injected them with fresh bacteria. The chickens did not become ill. Pasteur reasoned that the bacteria became less deadly due to exposure to oxygen.
In 1885, Louis Pasteur’s Rabies vaccine was the next to make an impact. Rabies is a viral disease usually transmitted through an animal bite, for example, from stray dogs. Viruses are small infectious agents that replicate quickly and have a high mutation rate, like the current Novel Corona Virus (Covid-19).
Pasteur produced the Rabies vaccine by attenuating the virus in rabbits - by passing the virus through rabbits, he made the virus less dangerous to human hosts. After successfully protecting dogs from the disease, Pasteur agreed to treat his first human patient, a nine-year-old boy who had been severely attacked by dogs with little chance of survival. Pasteur injected the boy daily with a series of progressively more virulent doses of the vaccine from the rabies-infected rabbits. The boy was saved.
Modern vaccine development
The middle of the 20th century was an active time for vaccine research and development. Between 1890 and 1950, there was much bacterial vaccine development, including the Bacillis-Calmette-Guerin (BCG) vaccination, which is still given to children today.
Vaccines against diphtheria, tetanus, pertussis or whooping cough (given in combination as DTP vaccine or DPT vaccine), anthrax, cholera, plague, typhoid, tuberculosis, Measles, Mumps and Rubella (MMR vaccine) and more were developed through the 1930s. In the 1990s, vaccines became available for Hepatitis A and B, Varicella (chickenpox) followed by vaccines for Haemophilus influenzae Type b (Hib) and Rotavirus.
Modern vaccine research is driven by innovative techniques, with recombinant DNA technology and new delivery techniques. Incidentally, Serum Institute of India is now the world's largest vaccine manufacturer by number of doses produced and sold globally (more than 1.5 billion doses) which includes Polio vaccine as well as DTP, Hib, BCG, r-Hepatitis B, MMR vaccines. Vaccines manufactured by the Serum Institute are accredited by the World Health Organization and are being used in around 170 countries across the globe in their national immunisation programs.
As Serum Institute and global pharmaceutical companies race to roll out the most effective and safe vaccine for the Covid-19, we have Edward Jenner to thank for introducing us to Vaccines that have saved billions of lives worldwide.