The Continued Life of a Dead Virus

By Matthew Pesesky

In the complex world of global pandemic control, smallpox (Variola major/minor) is the foremost medical success story, the only human disease ever eliminated from the natural world. For public health officials, smallpox’s 1977 eradication (Certified by the WHO in 1979) has become an inspirational touchstone for the elimination of other diseases such as polio, guinea worm disease, measles, and malaria. Yet the continued existence of live smallpox samples is the subject of intense debate and demonstrates that global health issues are neither isolated from political and security concerns nor can always be resolved quickly or easily.

Some smallpox samples still survive in the United States at the Centers for Disease Control and Prevention in Atlanta and in Russia at the Siberian-bound VECTOR Institute. Whether or not to destroy these samples is the subject of long-running controversy. While “retentionists” consider the threat of bioterrorism sufficient to preserve the disease for study and prevention, “destructionists” favor complete elimination of the pathogen.

In the millennia before the WHO confirmed its eradication, smallpox was the world’s deadliest disease, killing, blinding, and scarring millions. Evidence of its destruction, with 30% or higher death rates, appears on the faces of mummified pharaohs and in the haunting photographs of the last generations of children afflicted. Smallpox altered the course of history, particularly in the Americas. Traveling airborne from early-arriving Europeans and Africans to American Indians, it decimated populations of indigenous peoples from Chile to Canada, opening a path for Pizarro, Cortez, and other conquistadors to wrest power from those peoples.

In the early 1700s, European elites began variolation, or inoculation with live smallpox, to mitigate the risks of future infection. Although variolation was less dangerous than acquiring smallpox naturally, death rates remained unacceptably high. After observing that milkmaids with cowpox, a mild relative of smallpox, did not contract Variola, English scientist Edward Jenner began immunizing patients with cowpox, creating the world’s first effective vaccine.

While there was still no cure, Jenner had created a reliable preventive measure. The World Health Organization, United States, the United Soviet Socialist Republics took the lead in a worldwide effort to eliminate the disease, beginning seriously in 1967 after approving the eradication effort in 1959.  Vaccination, however, often had side effects and did not confer lifelong immunity, requiring re-immunization and logistical innovation in regions where poverty, terrain, public weariness, and political instability were often concerns.   With an improved vaccine in tow, Dr. H. Mahler, WHO director-general at the time, described the smallpox eradication program as "a triumph of management, not of medicine."

Despite challenges of geography and the vaccine’s limitations, the smallpox program succeeded—a seminal moment for international cooperation in public health. While there were some immediate calls to destroy the virus, smallpox was preserved for study. Today, the United States, Russia, and much of Europe argue for continued research on smallpox to mitigate a bioterrorism strike, while many developing nations would prefer the disease’s complete elimination to prevent accidental release. Whether occurring accidentally or deliberately, smallpox release would be extremely dangerous due to the current low levels of smallpox immunity worldwide as a natural result of the 1977 elimination.

Retentionists call for the preservation of the samples to prevent and prepare for bioterrorism or the emergence of a similar disease. The possibility of clandestine stocks of the pathogen, either in the former Soviet Union or in rogue states such as North Korea and Iran, caused renewed interest in U.S. security circles after September 11. The discovery that the former U.S.S.R. weaponized smallpox has led retentionists to argue that smallpox-based weapons may still exist in unknown locations and pose a significant threat. To retentionists, this chance of rogue states or actors utilizing weaponized smallpox far outweighs the chance of accidental release, which has not happened since 1978. The mistrust, especially of rogue states, in some ways resembles the prisoner’s dilemma of nuclear disarmament. In response to the threat of reintroduction through bioterrorism, the United States and several other nations have produced large quantities of smallpox vaccine, yet there has been no global movement to raise vaccine stocks worldwide.

Destructionists believe the United States and Russia should bilaterally destroy their live smallpox samples, arguing the world is an inherently safer place without the disease. Destructionists, who are often medical professionals such as D.A. Henderson, argue the risk of theft or accidental release of remaining live samples outweighs the chance of an attack in a sample-free world. The destructionist view is also supported by many nations of South Asia and Africa, led by Iran, as their already-burdened health systems and limited budgets make them most susceptible to reemergence. If needed, they claim, there are enough existing smallpox vaccines to cover substantial populations and more can be produced without live samples due to the successful mapping of the smallpox genome. Over the past few years, the destructionist viewpoint has been gaining traction. In May 2011 the World Health Assembly concurred with the recommendation of the June 1999 World Health Assembly that all stocks of smallpox be destroyed. The Assembly, however, delayed its final decision on smallpox eradication until 2014, yet there is no reason to assume a resolution will occur at that date. The issue continues to be debated as the United States and Russia study the vaccine, looking to develop an antibiotic cure.

The debate between smallpox retentionists and destructionists is emblematic of numerous questions that confront our rapidly globalizing world. How should scarce medical research funding be distributed? Who has the right to make decisions regarding a global disease? How are disease and security interconnected? How should national borders dictate our global health strategies? What is the true risk of bioterrorism?

This choice—whether or not to destroy our last living samples of smallpox—is a historic and unprecedented one, tied inextricably to the epidemics of the past and the uncertainty of the future. The ghosts of smallpox’s victims still haunt humanity, and the thought of its resurgence through bioterrorism or unintentional release gives reason to carefully debate the next step. Even as medical science allowed its eradication from nature, political divisions and distrust have ensured that smallpox remains a part of our collective existence. As things stand, destroying the final samples is only partly a medical decision, and may remain a bridge too far.

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