How the smallpox eradication campaign highlights the ongoing importance of vaccination despite complacency

The successful campaign to eradicate smallpox, driven by mass vaccination and global collaboration, exemplifies the vital role of immunisation in saving millions of lives , a legacy now threatened by declining coverage and misinformation.

Edward Jenner’s 1796 observation about milkmaids and cowpox helped launch a medical revolution. By showing that a mild infection could protect against smallpox, Jenner laid the groundwork for vaccination, a preventive tool that would eventually help rid the world of one of its deadliest diseases.

The World Health Organisation says smallpox remains the only human disease eliminated through deliberate global action. After an intensified eradication campaign began in 1967, the last known natural case was recorded in 1977, and eradication was officially declared in 1980. WHO and the US Centers for Disease Control and Prevention both describe the campaign as one of public health’s greatest achievements.

That success did not happen by accident. WHO’s eradication programme relied on mass vaccination, surveillance and containment, with teams working to reach remote communities and stop outbreaks before they spread. In 2020, WHO noted that the effort involved hundreds of millions of vaccinations and showed the value of international co-operation against a common threat.

The scale of the wider vaccine benefit is striking. A 2024 WHO study published in The Lancet estimated that routine immunisation against 14 pathogens has saved 154 million lives since 1974, most of them in early childhood. The study also found that for every death prevented, vaccination has added an average of 66 years of healthy life. WHO says immunisation now helps prevent between 3.5 million and 5 million deaths each year.

Yet the very success of vaccines can make their value easier to ignore. As coverage falls in some communities, diseases such as measles have reappeared, helped by misinformation and complacency. Health experts say the challenge is to remember what prevention has spared us: children who never became ill, outbreaks that never took hold and deaths that never happened.