Only one human disease has been fully eradicated through vaccination: smallpox. That’s it. Despite the enormous success of global vaccination programs against dozens of infectious diseases, smallpox remains the sole human disease wiped off the planet permanently. A second disease, rinderpest, was eradicated in animals through vaccination in 2011. Several other diseases are close to eradication, and vaccines have eliminated many diseases from specific regions, but the complete, worldwide, permanent victory that defines eradication has only been achieved twice in all of history.
What “Eradicated” Actually Means
Eradication has a precise definition that separates it from related terms that often get mixed up. The World Health Organization defines disease eradication as the permanent reduction to zero of worldwide infection, achieved through deliberate effort, after which intervention measures are no longer needed. That last part is key: once a disease is eradicated, you can stop vaccinating against it entirely.
This is different from elimination, which means reducing a disease to zero in a specific geographic area while continuing vaccination to prevent it from returning. Measles, for example, has been eliminated from several countries but still circulates globally. And disease control simply means reducing a disease to manageable levels through ongoing effort. Many vaccine-preventable diseases like whooping cough and influenza fall into this category.
Smallpox: The Only Human Disease Eradicated
The last naturally occurring case of smallpox appeared in Ali Maow Maalin, a hospital cook in Merca, Somalia, who developed symptoms on October 22, 1977. On May 8, 1980, the World Health Assembly officially declared the world free of smallpox, nearly two centuries after Edward Jenner first demonstrated that vaccination could protect against the disease.
Smallpox was an ideal candidate for eradication for several biological reasons. It had no animal reservoir, meaning the virus could only survive in humans. Infected people developed visible symptoms, making cases easy to identify and isolate. The vaccine was highly effective, stable enough to transport to remote areas, and provided long-lasting immunity. These features allowed health workers to use a “ring vaccination” strategy, vaccinating everyone around a confirmed case to contain outbreaks rather than needing to reach every person on Earth.
Because smallpox is eradicated, routine vaccination stopped worldwide. This alone has saved enormous ongoing costs and prevented the side effects that came with the vaccine itself.
Rinderpest: The Animal Equivalent
In 2011, the world declared victory over rinderpest, a devastating viral disease of cattle and other livestock. The last case had been reported a decade earlier. Rinderpest remains the only animal disease ever eradicated and stands alongside smallpox as one of just two diseases of any kind eliminated from the planet through vaccination. The achievement was particularly significant for food security in Africa and Asia, where rinderpest outbreaks had historically killed up to 90% of infected herds.
Polio: Close but Not There Yet
Polio is the disease most people assume has been eradicated, and it’s close. Two of the three types of wild poliovirus have been officially declared eradicated: type 2 in September 2015 and type 3 in October 2019. But wild poliovirus type 1 still circulates in two countries, Afghanistan and Pakistan, which keeps polio from meeting the definition of full eradication.
In 2025, as of September, 28 cases of wild poliovirus type 1 were reported: 4 in Afghanistan and 24 in Pakistan. That is a dramatic reduction from the estimated 350,000 annual cases in 125 countries when the Global Polio Eradication Initiative launched in 1988, a decline of over 99%. The economic analysis of the polio eradication effort estimates net benefits of $40 to $50 billion between 1988 and 2035, with low-income countries accounting for roughly 85% of those benefits. In the United States alone, polio vaccination efforts since 1955 have generated an estimated $220 billion in net benefits from prevented treatment costs.
The remaining challenge is reaching children in conflict zones and areas with fragile health infrastructure. Until type 1 is eliminated from its last two footholds, vaccination must continue globally to prevent reintroduction.
Diseases Eliminated Regionally but Not Eradicated
Several diseases have been eliminated from large parts of the world through vaccines without achieving global eradication. These successes are real and save millions of lives, but they require continued vaccination to maintain.
Measles has been eliminated from multiple countries and regions. In the WHO South-East Asia Region, five countries (Bhutan, DPR Korea, Maldives, Sri Lanka, and Timor-Leste) have sustained measles elimination. Maintaining this status requires at least 95% vaccination coverage with two doses in every district. When coverage drops, measles returns quickly, as several countries have experienced in recent years.
Rubella has similarly been eliminated from parts of the world, with Maldives and Sri Lanka sustaining elimination in the South-East Asia Region. Neonatal tetanus is another example of a disease that has been eliminated from many countries through vaccination but persists in areas with limited healthcare access.
Why So Few Diseases Can Be Eradicated
The shortness of the eradication list is not a failure of vaccines. It reflects how extraordinarily difficult eradication is. A disease needs specific biological features to even be a candidate. It must infect only humans (no animal reservoir where the pathogen can hide), produce recognizable symptoms (so every case can be found), and have an effective, practical vaccine. The pathogen also cannot persist silently in carriers who show no symptoms, since invisible transmission makes it nearly impossible to track and stop every chain of infection.
Most vaccine-preventable diseases fail at least one of these criteria. Influenza constantly mutates and infects animals. Tetanus lives in soil indefinitely. Tuberculosis can remain dormant in a person’s body for decades. These diseases can be controlled and even eliminated regionally, but the biology makes worldwide eradication impractical with current tools.
Guinea Worm: Near Eradication Without a Vaccine
Guinea worm disease is worth mentioning because it is on the verge of eradication through public health measures alone, without any vaccine. In 2024, only 15 human cases were reported worldwide, confined to Chad and South Sudan. The WHO has certified 200 countries and territories as free of transmission, with six countries still awaiting certification: Angola, Chad, Ethiopia, Mali, South Sudan, and Sudan. If successful, it would become the first parasitic disease eradicated and the first achieved purely through behavioral and environmental interventions like water filtration rather than vaccination.