For a disease that was declared extinct nearly 35 years ago, smallpox continues to do a remarkable job of dividing politicians, scientists and nations.

The World Health Assembly, which governs the World Health Organisation, has been embroiled in a decades-long debate about the fate of the remaining research specimens of the viral disease—which killed some 300 million people in the last century and may have caused the decline of entire civilisations. On May 19-24, representatives of the nations in the assembly will meet once again in Geneva and weigh evidence to decide if smallpox research should continue, or if the live specimens of the virus that causes the disease—held in secure labs in Russia and the US—should be destroyed forever.

In advance of this decision, a group of microbiologists have argued for a temporary reprieve for the last remaining stocks of the virus. Their opinion paper, published in PLOS Pathogens, argues that the world still needs these samples.

The history of smallpox eradication stretches back to 1959, when the member states of the young World Health Assembly voted to eradicate the disease with a global vaccination campaign. The last known case of smallpox occurred in 1978 in Birmingham, England, when a medical photographer named Janet Parker, who worked above a bio-safety lab, died after contracting the disease. The world held its breath for two years, and in 1980, smallpox was declared eradicated.

Grant McFadden, a molecular biologist from the University of Florida who co-authored the PLOS Pathogens paper, has been doing smallpox research for about 15 years. “Although smallpox is gone, there are a number of ways it could reappear again in human population,” he told Quartz. For that reason, the WHO decided on a set of research milestones that, once reached, would mean the last specimens could be safely destroyed.

Chief among these was the imperative that two drugs be developed for treating active smallpox infections. The WHO decided two antiviral drugs with different ways of attacking the disease were necessary, in case either of the drugs caused adverse reactions in some people, or the disease developed a resistance.

As the “destructionists” point out, there are now two such drugs very close to approval in the US. In fact, the US government has already paid close to $500 million for one of them. “My view is that [the drugs] are pretty much done,” Dr. Geoffrey Smith of Cambridge University in England told Quartz. Both drugs are currently in phase II of clinical trials (out of three phases). “I don’t think you need live virus for the limited objectives that remain.”

Also, the destructionists point out, it’s better not to have samples of a deadly virus hanging around, even in a secure lab. The risk of the drug escaping is small, but it does exist. (The 2001 anthrax attacks in the US were perpetrated by a CDC biologist who stole samples of the bacteria from his lab.) They also point to the cost of holding onto the samples: Maintaining the high-security facilities needed to house the disease is incredibly expensive. That’s money that could be spent to fight new threats, Smith argues, rather than “on a disease that hasn’t killed anyone for 40 years.”

The “retentionists” see the same set of facts through a different lens. For one thing, the authors of the PLOS Pathogens paper point out, the smallpox drugs aren’t yet ready for consumption. “Its not that we don’t think that the two existing compounds aren’t promising,” said co-author Inger Damon, a Centre for Disease Control physician-scientist who works with smallpox. “It’s just that they’re not finished yet.”

If either or both drugs don’t make it through to licensure, then drug research will have to begin anew, Damon told Quartz. And if the live strains of smallpox are destroyed, those efforts would be severely crippled, she says. Once the drugs are approved, she argues, that would be the time to destroy the remaining viruses.

Although it’s unlikely, it’s possible that rogue strains of the disease exist. As an example, McFadden points to 1992, when a Soviet defector told the CIA that the USSR had been stockpiling smallpox and avoiding compliance with biological warfare treaties. “It is impossible to estimate the likelihood that there are stocks outside of the two declared repositories,” said McFadden. This is a risk governments seem to be considering too: In fact, it was the anthrax scares of 2001 that convinced the WHO that the threat of bioterrorism was real enough to extend the smallpox eradication deadline through the early 2000s.

Smallpox research has also paid off in other ways, say McFadden and Damon. For one, it has helped develop treatments for other orthopox viruses related to smallpox, including monkeypox in Africa, vaccinia in Brazil, and an as-yet-unnamed pox virus in the Republic of Georgia.

And if the WHO does decide that it’s time to end smallpox research, how does one destroy a virus? McFadden guesses that there would be a ceremony at each of the secure facilities, and then the remaining specimens would be doused in a high-temperature, high-pressure steam. This sounds effective, though perhaps not as satisfying as dropping the viruses into Mt Doom (video).


A glass sculpture of variola, the virus that causes smallpox. Photo credit: Luke Jerram


This post originally appeared on Qz.com.