Variolation Explained !! Technique, Risks, History, Edward Jenner & Current Smallpox Vaccine Requirements

Variolation was a method of inoculation which was used to immunize people against Smallpox. In this technique, the materials extracted from the scabs and pustules of an infected person were injected into a person who had not developed smallpox. This resulted in the development of mild infection of smallpox in the person but they developed an immunity against the smallpox virus.

The procedure carried risks as some patients may develop a severe infection which could lead to the development of many complications in the patients. The materials which were used for variolation were extracted by scratching the scabs and pustules of an infected person. This method was replaced when Edward Jenner introduced the smallpox vaccine derived from the cowpox virus.

Currently, variolation is not used anymore as there are numerous vaccines available to provide immunity to individuals. These vaccines are safer than variolation and do not lead to the onset of any severe side effects and complications in the patients.


Variolation is a method used to provide artificial immunity to people by exposing them to a small quantity of the virus. This produces a milder form of infection in the exposed people but they develop an immunity against the virus and do not develop a full infection when exposed to the virus again. Variolation was the most commonly used method of immunisation before vaccines were invented and it was successful in most cases.

However, many individuals developed some complications associated with the variolation such as a full infection of smallpox. This gathered opposition against the method from many medical practitioners however it did manage to become the mainstream method of immunisation in the 1700s. The method was replaced when a much safer method of immunisation was invented by Edward Jenner, known as Vaccination.

This method is now used to immunise people against various diseases and variolation is not used anymore. The article given below will explain all the details regarding variolation, its history and origin, technique, risks and currently used method of vaccination against smallpox.

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History of Variolation 

The origin of variolation is not clear and no scientist or researcher has been credited for its development. However, there are many pieces of evidence which can help us to trace its origin in India, China and Sudan.

  • India- India has been suggested as a possible origin of variolation and for its spread in Europe. There are literary accounts of Europeans which mention that variolation has been practised by Brahmins for many hundreds of years. These accounts have been questioned over time however it was found that variolation was still performed in Bengal in 1768.
  • China- The literary pieces of evidence documenting the use of variolation date back to the fifteenth century. They used a method known as nasal insufflation in which they blew the powdered form of smallpox material into the nostril of the person. This powder was most commonly obtained from the scabs of a person having a mild infection of smallpox. These scabs were left to dry out for three to four days and then powdered. The persons who were variolated were treated to be as infectious as a full-blown infection of smallpox and were kept separated from other people until the rash disappeared. Variolations were being performed in China in the 1700s as the Royal Society in London received reports of its practice in China.
  • Sudan- Two similar methods were seen in the Middle East and Africa in the late eighteenth and early nineteenth centuries. One practice was that a mother would visit the house of a newly infected person and tie a cloth around the patient’s arm. Then she would make a bargain regarding the price of the pustule. Once a deal would be made, the mother would take the cloth back to her house and tie it around the arm of her child.

Another practice was similar to the variolation methods used in other countries. In this, the material extracted from the scabs of the patient was rubbed into a cut made on the person’s skin. 

Variolation Explained !! Technique, Risks, History, Edward Jenner & Current Smallpox Vaccine Requirements

Edward Jenner

There were various drawbacks associated with variolation. The most severe drawback was that the people who had been variolated and had developed the symptoms of smallpox were able to spread the virus to other people. This spread increased largely in numbers and began to outweigh the success of Variolation.

Another drawback was that sometimes, it did not prevent a second attack and patients did contract the infection. Hence many individuals started looking for alternative ways to immunize people. At this time, many individuals were interested to use the material of another mild disease, cowpox, to prevent an infection of Smallpox.

Particularly, Edward Jenner came to know about a local rumour which said that people who had acquired cowpox were immune to smallpox. Cowpox was an infectious disease similar to smallpox but milder and it spread to humans when they came in contact with an infected cow. Edward Jenner researched this rumour and produced a vaccine. He used this vaccine on his gardener’s son, James Phipps, in 1796.

After the vaccination, he exposed James to the virus of smallpox several times but the infection did not occur. Vaccination proved to be a safer method of immunization against Smallpox. The use of Variolation started to decline after the widespread use of the vaccine for smallpox.

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Technique of Variolation 

It was widely known that if a person survived an infection of Smallpox then they could not get infected again. This formed the basic principle of variolation and the technique of variolation included the exposure of the patients to the virus. The following method was used to variolate people.

  • Isolating the matter of smallpox- The first step of variolation was the isolation of the smallpox matter from an infected person. This was done by either poking a needle in a fresh smallpox pustule and then removing the liquid matter from the pustule. This matter was then either dried or stored in a vial for later use.
  • Transferring the matter of smallpox to another person- This matter was then transferred to a person who had never been infected by the virus. The best way to transfer this matter was to get it under the skin of the patient. This was done by making a small cut on the arms or legs of the patient and then rubbing the matter in the wound. The best method of cutting was that the wound should not draw any blood from the site.
  • Looking for the signs of infection- After the transfer was complete, the variolated person was observed for any signs of infection or immune response. This was usually characterised by fever and pustules over the site of variolation. These symptoms cleared in a few days and the occurrence of these meant that the procedure was successful.

Risks of Variolation 

There were many risks associated with this method as many individuals were careless in its practice. Common risks associated with variolation were the following.

  • Development of a full infection of Smallpox- Sometimes, people who were variolated developed a full infection of smallpox. This may have been because they had weak immune systems or they were exposed to too much of the virus.
  • Spread of Disease to other people- Many variolated people could spread the infection to other people as long as they had the symptoms of the disease. Because of this, many variolated people spread the virus to healthy people which lead to many epidemics.
  • Infection with other diseases- If a donor of the smallpox virus had a previous chronic disease then this disease could also spread to anyone variolated with their matter. A common example of this is the spread of Syphilis in many people as the disease spread from the blood of the infected person.


  • Smallpox was an infectious caused by the variola virus of the Orthopoxvirus family. The disease has been declared eradicated by the WHO in 1980 and the last known infection of smallpox occurred in 1977 in Bangladesh. The disease was deadly and at least 3 out of the 10 infected people would die within 10 to 11 days of infection. 
  • The initial symptoms of the disease included fever and vomiting after which the patients would develop ulcers in their mouths and skin rash. The rash would then turn into fluid-filled blisters with a dent in their centre. This was the characteristic feature of smallpox and these blisters scabbed all over the body leaving behind severe scars. 
  • The disease could be spread through contact with an infected person or with an object contaminated with the virus. Some people who survived smallpox had extensive scarring and were often blind.
  • All the patients who survived smallpox did not develop it again in their lifetime. This was because the body of these patients developed an immunity against the disease.
  • There was no treatment for smallpox hence the only option left to people was prevention. The best method of prevention against the disease is vaccination. 
  • Because of the vaccination drives initiated by the WHO, the smallpox disease has been eradicated from the world and no live case of smallpox has been reported since 1977.

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Current Smallpox Vaccine Requirements

The current smallpox vaccine is made from a virus known as vaccinia. It is a poxvirus and is very similar to the smallpox virus. This vaccine does not contain the smallpox virus hence it cannot cause smallpox in anyone.

Since smallpox has been eradicated since 1980, people are not vaccinated against the disease routinely. Many countries have stockpiles of smallpox vaccines in case the virus does return. The following vaccines are available for smallpox.

  • ACAM2000- This is a replication-competent vaccine and provides active immunization against smallpox disease in people who are at high risk of infection. It contains the vaccinia virus and does not lead to the development of smallpox in people. However, some people may experience fever, headache and body ache after vaccination which goes away in 1 or 2 days. The virus can also spread from a vaccinated person to an unvaccinated person hence the site of vaccination requires special care to prevent the virus from spreading.
  • JYNNEOS- The JYNNEOS vaccine is a replication-deficient smallpox vaccine and is used for protection against smallpox and monkeypox. It is an attenuated live virus vaccine and is used for vaccination in people older than 18 years with certain immune deficient conditions such as HIV infection or atopic dermatitis. It does not lead to the development of severe side effects in such patients. This vaccine is used only when there is a smallpox emergency based on the risk of exposure and contraindications of ACAM2000.
  • Aventis Pasteur Smallpox Vaccine (APSV)- The Aventis Pasteur Smallpox Vaccine is another replication-competent virus vaccine. It is similar to ACAM2000 and will be used when ACAM2000 has been exhausted or is not available easily. It can also be used when ACAM2000 is contraindicated.
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FAQs Related to Variolation 

What is Variolation?

Variolation is a method used to provide artificial immunity to people by exposing them to a small quantity of the virus. This produces a milder form of infection in the exposed people but they develop an immunity against the virus and do not develop a full infection when exposed to the virus again. 

What is the difference between variolation and vaccination?

Variolation was a method in which a person was exposed to a smaller quantity of the virus causing smallpox. This led to the development of mild infection of smallpox and the individuals developed immunity against the virus of Smallpox. On the other hand, vaccination involved exposing people to a similar but milder infection to develop their immunity against the virus of smallpox.

Is Varioloation still used?

Variolation is not used anymore as it carried many risks along with it. The people who were variolated could develop a full infection of smallpox if they had weak immune systems or if they were exposed to a large quantity of the virus. They could also spread the virus to other people as long as they had the symptoms and this led to the onset of many epidemics in many regions.

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