How did humanity win the 3,000-year history of fighting smallpox?

Infectious diseases are the endless enemy of human survival. Three centuries ago, humans completed a clean and effective counterattack against infectious diseases for the first time, which was a milestone battle.

Smallpox, called "the greatest genocide in human history" by historians, lasted for at least three thousand years and spread across every continent in the world. According to incomplete statistics, at least hundreds of millions of people died of smallpox in Europe in the 18th century, from civilians to nobles and even kings, all were equally affected by smallpox.

The horror of smallpox lies in its strong infectiousness and mortality rate . The basic infectious index of the smallpox virus is 5.0, and the mortality rate is close to 30% . The mortality rate of infants and young children with underdeveloped immune systems is much higher than that of adults. Most of the other two-thirds of survivors will have lifelong sequelae, ranging from scars all over the body to impaired physical functions.

The person who completely saved the world from the darkness of smallpox was a country doctor on horseback - Edward Jenner from Berkeley Valley in England.

Portrait of Edward Jenner

How did vaccines come about? Most people may have heard the story of how Dr. Jenner accidentally discovered that milkmaids who had had cowpox could resist smallpox, but few people know how much this doctor, named Jenner, devoted his entire life to the invention and promotion of vaccines.

Born in 1749, Jenner showed a keen interest in nature at an early age. He balanced his interest in natural history with his excellent academic performance. However, the young Jenner did not follow the family tradition to engage in high-status clergy work. Instead, he chose medicine and went to London to study under John Hunter , a famous doctor in the medical field at the time. This mentor had a profound influence on Jenner's life. The two were both teachers and friends, and their cooperation and friendship came to an abrupt end when Hunter died of coronary heart disease in 1793.

Compared to his hometown of Berkeley Valley, London was prosperous and full of opportunities. However, Jenner "had no ambition" and declined the invitation to become Hunter's assistant. He also gave up the precious opportunity of a global scientific expedition (which would help Darwin to establish the theory of evolution in the future). He resolutely returned to his hometown and became a country doctor who traveled around on horseback to practice medicine.

In Berkeley, he quickly became famous for his good medical ethics and medical skills. Not only was Jenner proficient in his profession, he also had a strong interest in music and poetry and had profound attainments. He was also elected a fellow of the Royal Society of London for his achievements in amateur natural history research.

1788 Jenner's paper on his observations on the cuckoo

It was such a doctor like Jenner who had an orthodox medical background and was rich in observation and reasoning abilities . After accumulating a wealth of treatment experience and a lot of practical experience in natural history science, he was able to combine profound theory with bold practice in his encounter with cowpox, and finally invented an absolutely safe and effective smallpox vaccine.

According to the research of British scholar Joseph Needham, the Chinese method of artificially "vaccinating" to prevent smallpox may have appeared in the Song Dynasty or even the Sui Dynasty . Later, the smallpox vaccination method spread to Europe through the Middle East. Before Jenner was born, Britain had vigorously promoted smallpox vaccination with the support of nobles such as Lady Montagu and the royal family.

Lady Montagu and her son

Although smallpox vaccination is effective, it is not safe and cannot be called a vaccine. Smallpox vaccination is a method in which healthy people actively come into contact with the virus of an infected person. Even if the toxicity is weakened, it still has a considerable ability to cause disease, and the mortality rate is as high as 2%. Even in the "Introduction to Smallpox" during the Jiaqing period of the Qing Dynasty, it is described that smallpox vaccination using nasogastric feeding "still has a one in ten chance of failure", that is, the mortality rate may be as high as 10%.

Smallpox vaccination was a matter of life and death. When the 8-year-old Jenner was vaccinated, he underwent a brutal 6-week preparation. Fortunately, he recovered with difficulty.

In order to prevent smallpox, healthy humans had to bear extremely high costs and risks, which made this method difficult to truly popularize and could not play the role of isolating smallpox. Even so, there is no doubt that the smallpox method pointed the way for the invention of vaccines.

Painting depicting Jenner's inoculation

In 1768, a doctor named Foster discovered during the smallpox vaccination process that some people did not show normal vaccination reactions after being vaccinated, and without exception, these people had had cowpox.

Foster once called on other doctors at a local medical gathering to study the connection between cowpox and smallpox. Unfortunately, he had a preconceived notion that the side effects and protective power of cowpox had no advantages over the then-mature human pox vaccination, and mistakenly believed that not all "cowpox" could prevent smallpox, so he had no interest in conducting further research, and the doctors present basically agreed with his idea.

At that time, Jenner, who was only 19 years old, was just an apprentice and was not qualified to attend medical gatherings. However, Jenner's teacher, Dr. Ludlow, was also present at the gathering. When Jenner heard about this discovery, the seeds of exploration and truth were planted in his heart. When he finally had the qualifications to vaccinate smallpox, Jenner conducted a lot of careful observation, research and verification on the cowpox patients he could contact.

In 1798, he published his first influential paper on smallpox vaccination: An Inquiry into the Cause and Effect of Vaccination against Smallpox . Jenner meticulously recorded the cases of immunity to smallpox after he had observed and confirmed the cases repeatedly, and put forward his own findings:

"When the horse virus infects humans directly, it does not ensure that people will acquire resistance to smallpox, but when the virus is transmitted from horses to cows, the pus produced in the cow's teats can definitely make people resistant to smallpox."

An Inquiry into the Cause and Effect of the Smallpox Vaccine

In an era when diseases and plagues were still widely regarded as demonic forces, Jenner was very cautious and bold in making such an advanced speculation in his paper:

"The agent of smallpox was a peculiar pathogenic agent produced by sick horses, and this may have occurred again and again until new changes occurred in the agent making it contagious to man, which finally led to this common plague capable of causing devastation among mankind."

It is not difficult for us to judge today that this conclusion is not accurate, but it was extremely rare in the scientific community at that time. After all, it was not until more than a hundred years later that people finally discovered that bacteria and viruses were the source of human disease.

In 1799, he had gained full confidence in his views through practice, and published "Further Views on Smallpox Vaccination", and began to call for cowpox vaccination to the public.

Jenner published six papers on vaccines in his lifetime, the first three of which were related to the invention of vaccines. These valuable documents of great scientific value are strong evidence that he was the inventor of vaccines.

Statue of Jenner in Gloucester Cathedral

Before Jenner invented a truly safe smallpox vaccine, a doctor had gained family prestige and huge wealth by simply improving the smallpox vaccination method with a mortality rate as low as 0.2%, and expanded his business to many countries. If Jenner was willing, his smallpox vaccine would continue to bring him immeasurable fame and wealth.

But just as the young Jenner chose the countryside over London, the middle-aged Jenner chose to help the world over fame and fortune. He announced his invention to the world for free, and throughout his life, he campaigned for the promotion of smallpox vaccine , making it widely spread around the world, saving an equally incalculable number of lives.

In May 1980, smallpox was declared completely eradicated by the World Health Organization, becoming the first and only infectious disease in human history to be truly eradicated.

In 1980, smallpox was declared eradicated

Today, immunology has long been at the forefront of the medical field. Vaccines have saved countless people from diseases, and even the prevention of cancer, the king of all diseases, has achieved certain results. The existence of vaccines has become commonplace and is closely related to each of us. It is difficult for us to imagine what the world would be like without vaccines.

Could Dr. Jenner have imagined that his achievements would have such a great impact more than two centuries ago? Probably not. But his valuable qualities as a doctor safeguarded the victory of the battle for human survival.

There is an endless war between humans and diseases. Apart from known enemies, we can never foresee when and where the next rampant demon will appear.

But we have won and we will never give up.

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