Smallpox is a serious infectious disease caused by the Variola virus, known historically for its high mortality rate and devastating global epidemics. The virus no longer circulates naturally anywhere in the world, thanks to an intense global effort to eliminate it. This successful eradication marks one of the greatest achievements in public health history. Today, the virus is found only in a few highly controlled laboratory environments.
The Global Eradication of Smallpox
The successful elimination of smallpox resulted from an intensive, decades-long effort led by the World Health Organization’s global eradication program. This campaign relied heavily on a strategy known as “ring vaccination,” where health workers swiftly isolated outbreaks and vaccinated every person who had been in contact with an infected individual. This targeted approach proved highly effective because the Variola virus only infects humans and has no animal reservoir.
The final recorded naturally occurring case of smallpox was identified in October 1977 in Somalia. The patient recovered, and subsequent surveillance confirmed that the chain of natural transmission had finally been broken worldwide. This event demonstrated the profound success of coordinated international public health measures.
Following three years of monitoring to ensure no hidden pockets of the disease remained, the World Health Assembly officially declared smallpox eradicated from the planet in May 1980. This declaration meant the disease had been permanently removed from the wild, making it the first human infectious disease to be completely eliminated globally. Once the virus was eradicated, the focus shifted to managing the remaining laboratory stocks used for research.
Designated Official Virus Repositories
Following the global eradication, the international community agreed that all remaining Variola virus samples should be consolidated into just two designated, high-security facilities. These are the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, in the United States, and the State Research Center of Virology and Biotechnology VECTOR (SRC VB VECTOR) in Koltsovo, Russia. These two sites are the only places where live, infectious smallpox virus is officially maintained today.
The physical storage of the virus requires the highest level of biological containment, known as Biosafety Level 4 (BSL-4). This designation mandates specialized ventilation systems, multiple layers of access control, and full-body positive-pressure suits for all laboratory personnel. The BSL-4 environment ensures that the virus cannot escape the facility and poses no risk to the surrounding community or the environment.
Storing the world’s remaining smallpox stocks is governed by strict international agreements and oversight protocols established by the World Health Organization. International teams conduct regular, rigorous inspections of both the CDC and VECTOR facilities to verify compliance with safety, security, and inventory standards. This oversight process maintains transparency and accountability regarding the handling of the dangerous pathogen.
The retained samples consist of a diverse collection of strains, including historical isolates from various geographical regions and time periods. This genetic diversity is maintained because different strains may exhibit unique properties important for future research into vaccine efficacy and antiviral drug development. The integrity of these samples is paramount to the ongoing scientific work.
Why the Remaining Stocks Are Maintained
The decision to retain these stocks, rather than destroy them entirely, stems from their recognized value for ongoing public health protection. The primary scientific reason for maintaining the virus stocks is to facilitate the development of newer, safer vaccines and more effective antiviral treatments. Researchers use the live virus in highly controlled settings to test the efficacy of new drug candidates against the actual pathogen. This research is aimed at creating medical countermeasures that could be deployed rapidly if the disease ever reappeared.
The existence of the retained samples also serves a preparedness function for global biodefense efforts. Scientists must understand the virus’s biology, including its genetic characteristics and virulence factors, to anticipate and counter any potential accidental release or deliberate misuse of the pathogen. This preparation is a necessary precaution in a world where biological threats are a continuing concern.
The eventual fate of the remaining Variola virus stocks is a topic of ongoing international scientific and ethical debate. Some experts advocate for the complete destruction of the samples to eliminate any risk of accidental release entirely. Others argue that destruction would be premature, potentially hindering future scientific breakthroughs necessary to protect humanity from related orthopoxviruses or future engineered threats.