How Smallpox Became the First Disease to Be Eradicated

On May 8th, 1980, the World Health Organization declared that smallpox, an infectious disease was successfully eradicated, meaning fully eliminated from our planet.

Considered one of the largest achievements in global health, the eradication of smallpox is the only time in history where humans have successfully rid themselves of a disease.

But…how exactly was this done? There were no guidelines, tips, or even strategies — nothing for health officials to follow. Yet, they somehow managed to pull off one of the CRAZIEST feats in human history!

A Brief History of Smallpox

Smallpox is an acute contagious disease, as a result of the variola virus. Whilst the origin date is not known, some believe that it has been around since the Egyptian Era (at least 3000 years ago!!) by identifying similar disease characteristics on mummies.

According to the Centers for Disease Control and Prevention, traces of smallpox were found on Pharoah Ramses V. (Image Courtesy: World Health Organization)

The two strains of smallpox are the variola major (30% fatality rate) and variola minor (<1% fatality rate).

There are 4 known types of smallpox:

  • Ordinary - the most frequent amongst the infected
  • Modified - more mild version, infected those who had already been exposed to the virus
  • Flat/Malignant - rare, infected mostly children
  • Hemorrhagic - severe, infected mostly adults
Boy with pustules all over his body (Image Courtesy: Public Health Image Library of the Centers For Disease Control And Prevention)

It is primarily spread through aerosols and air droplets as a result of prolonged face-to-face contact with an infected (especially if someone were to cough or sneeze on you). However, the disease could also be spread through materials (i.e. bedding) and in rare cases air transmissions.

After an incubation period of 12 - 14 days, the initial symptoms would include: high fever, body pain (most commonly had headaches and/or back pain), and vomiting (in some cases). Later on, a rash would spread throughout the body in the form of tiny sores called pustules. These sores would typically fall off in 3 weeks.

Those who didn’t pass away from the disease were left with severe scars. In some cases, smallpox caused a loss of sight afterwards.

Global Reaction

Killing +300 million people, smallpox quickly spread across the globe.

A graph showing the number of reported smallpox cases in 1952 (Image Courtesy: World Health Organization)

Before the invention of the vaccine, various methods were put into place in order to better understand the disease as well as prevent it in others.

One well-known method was variolation, where small amounts of pus from the sores of infected were put onto healthy people through scratches (4 - 5 scratch marks). This would allow people to not get reinfected. Still, this method was not 100% safe, with at least 3% of people dying from exposure to the disease.

The Eureka Moment

However, in 1798, Edward Jenner, an English physician discovered the vaccinia virus (cowpox) which would be used to control smallpox.

A portrait of Edward Jenner (Image Courtesy: The Jenner Institute)

The World Health Organization used the vaccine along with heavy monitoring of cases in order to fully eradicate the disease. To successfully implement contact tracing, certain activities were put into place.

These included:

  • Patient Interview - reviewal of the patient’s travel history, keeping tabs on anyone who was in close contact with this person when symptoms appeared
  • Identify Close Contacts - these people would be tested for symptoms, positive testers would be sent to healthcare facilities
  • Vaccination - the close contacts would receive the smallpox vaccine
  • Monitoring Period - those who received the vaccine would be monitored for 14 - 18 days, those who didn’t wish to receive the vaccine would be monitored for 18 days


In recent years, a newer version of the vaccine has been produced to substitute cell substrates for animal skin. As well, other versions of the vaccine included a 2nd generation vaccine using the same smallpox vaccine strain and a 3rd generation vaccine that is safer for those with dermatitis. However, these vaccines have yet to be used so the current effectiveness is unknown.

If the smallpox vaccine were to ever re-surface, the world would be prepared with a number of vaccines available for a safe and efficient immunization.

About the Writer

Hi everyone! My name is Alysha Selvarajah and I am a 15 y/o with a passion for solving global issues and emerging technologies. Currently, I am highly interested in viruses, cellular agriculture, space, and philosophy.

I would love to get in contact with you! Please shoot me a message on: Twitter, LinkedIn, or Instagram.



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