What is Variolation?

Medically Reviewed by Poonam Sachdev on April 08, 2022
5 min read

Variolation is an outdated medical technique that was used to protect people from smallpox. Doctors haven’t practiced the technique since the 19th century, though, when it was replaced with a more effective immunization strategy — vaccination

In historic contexts, smallpox variolation is the same thing as smallpox inoculation.

Variolation Technique

Both physicians and the general public have long understood that if you survive smallpox once, you can’t get it again. This is the main principle underlying variolation.

The technique allows people to transfer a small amount of the smallpox virus into uninfected individuals, hopefully immunizing them against a much worse natural infection.  

It’s existed around the globe in many different eras of human history, so the exact technique varies slightly. Still, the basic steps remain the same. They include: 

  • Isolating matter from a person infected with smallpox. This is done by poking something like a needle or lancet directly into a fresh smallpox pustule and removing liquid matter from this open wound. Pustules are a common symptom of smallpox.  
  • Transferring the matter to someone who has never been infected. The best way to transfer the virus is by getting the infected matter under the skin of the uninfected person. This was usually accomplished by opening a small cut in their arms or legs. In places where less information was available, people even tried wearing smallpox scabs or simply rubbing them on their skin. These techniques are far less effective and were never part of the official medical practice.  
  • Watching for an immune response. Most people will respond with mild symptoms — like a slight fever — shortly after the procedure. This was considered a sign that it worked. 

Afterward, most people shouldn’t be able to get smallpox again — no matter how much they’re exposed to it. 

Due to the very imprecise nature of this technique, there was always a chance that things could go wrong. Possible risks from the procedure include: 

  • Developing a severe smallpox infection. People with compromised immune systems or who received too much of the virus were at risk of developing a full-fledged smallpox infection. 
  • Spreading the disease to others. In some cases, variolated patients maintained high enough levels of the virus to create new epidemics of their own. 
  • Becoming infected with an unrelated disease. If the original person with smallpox also had other illnesses, these could be transferred too. One example is syphilis — which could be transferred through blood during the procedure.  

In general, the technique was quite effective. In medieval Europe, it seems that only 2% to 3% of people who were variolated went on to develop any of these negative risks. A study conducted in Boston — when Massachusetts was still a colony — found that variolation lowered your risk of death by smallpox from 14% to 2%. 

Variolation arose at many different times in history — probably when different communities were faced with the outbreak of extreme smallpox epidemics. 

In China, written accounts date variolation back to the 16th century. Popular tradition, though, claims that it was in use for hundreds of years before that. In India, there are references to the technique in ancient Sanskrit texts. This implies that it’s been in use there for thousands of years.

Written accounts indicate that the general populace in Europe was bartering money and goods for smallpox scabs as far back as the 16th century. It wasn’t incorporated into European medical practice, though, until the 18th century — when Lady Mary Wortley Montague had her two children variolated.   

It became common in the U.S. colonies too. A smallpox outbreak in Boston led Reverend Cotton Mather and Dr. Zabdiel Boylston to collect data on how well variolation worked. 

Eventually, the practice of variolation was replaced with vaccination — a more effective technique. In 1840, England banned the use of variolation, and the practice eventually died out around the world. 

The smallpox vaccine was most likely invented a number of times in different places. The discovery that finally led to its widespread use in the medical community is attributed to Edward Jenner in England at the end of the 18th century.  

Like many, Jenner had grown up hearing stories of how dairymaids were immune to smallpox — presumably because they had already survived a milder pox called cowpox. 

So, in May of 1796, Jenner took matter from the fresh cowpox lesions of a girl named Sarah Nelms. He then used this to inoculate an eight-year-old boy named James Phipps. After, the boy had mild symptoms but quickly returned to normal. 

In July, Jenner tried inoculating the boy with smallpox and didn’t see a single reaction. He concluded that the boy must be immune thanks to the cowpox. 

In his self-published results, he named the technique vaccination (“vacca” means cow in Latin). 

Many people were skeptical of vaccinations, but some doctors quickly understood the importance of the discovery. They began promoting the technique until it gained widespread acclaim. 

With improvements — and the later realization that boosters were needed — this vaccine helped to completely eradicate the disease worldwide in 1977.  

Edward Jenner is sometimes referred to as the father of modern immunology — not necessarily because he was the first person to invent vaccines, but because he brought the technique to the broader attention of the scientific world. This was accomplished through his effusive promotion of vaccination, as well as a reliance on evidence-based medicine — a standard in the field today. 

Jenner was born on May 17th, 1749 in England. His father was a reverend who died when Jenner was five. Orphaned, he lived with his older brother until moving to London when he was 21 years old. 

There, he became Dr. John Hunter’s student at St. George’s Hospital. After two years in London, he returned home to start his own medical practice. 

Jenner had a number of diverse interests in his life. He played the violin, wrote poetry, and built his own hydrogen balloon. He married in 1788 and had four children. 

After his discovery of the smallpox vaccine, he devoted most of his life to advocating for vaccination. He supplied doses to as many people as he could and surveyed the entire nation to assess the truth of his claims. 

He died from a stroke on Jan 26th, 1823. His contributions to science, though, continue to affect the world today.     

The United States stopped routine vaccination for smallpox in 1972. This is the year that the disease was fully eradicated from the U.S.

Although the disease was globally eradicated in 1977, a live version is available to people who need it. 

The modern vaccine consists of a live dose of vaccinia — a virus that causes a pox with much milder symptoms than smallpox. Historically, it’s effective at preventing a smallpox infection 95% of the time. You’ll need a booster after three to five years if — for some reason — you need long-term protection.