Since smallpox was eradicated from the human population in 1980, the only labs permitted and known to currently have stocks of the virus are the Centers for Disease Control in Atlanta, Ga., and VECTOR, a Soviet-era bioweapon lab that now carries out infectious disease research in Novosibirsk, Russia. The potential for the accidental or intentional release of smallpox from one of these locations created a discussion on whether these stocks should be maintained or destroyed to forever prevent smallpox from being reintroduced into the human population. As there are no FDA approved antiviral drugs against smallpox, and most of the population is unvaccinated against smallpox, the call for viral stock destruction was a reasonable one with the World Health Organization convening an annual meeting to discuss smallpox stock destruction..
But earlier this month, the CDC announced that six sealed vials of smallpox dating back to the 1950s were discovered in an old cold room of a Food and Drug Administration lab at the National Institutes of Health research campus in Bethesda. Further analysis of these vials by the CDC determined the virus that causes smallpox, Variola, was able to be grown from the stock recovered at the NIH. Not only had samples that were labeled as containing smallpox not been destroyed during the eradication efforts, they were stored in such a manner that allowed for viable smallpox virus to exist for over 60 years.
In light of the recovery of smallpox from these samples — their existence unknown for such a long period of time — it would be irresponsible to even continue the discussion of viral stock destruction at the CDC and VECTOR.
During the Cold War, both the U.S. and the USSR maintained offensive biological weapon programs that investigated the use of smallpox as a bioweapon. The Soviet program continued into the 1990s when the collapse of the Soviet Union brought the end to an organized offensive biological weapon program in Russia. However, it's known that nations like Iran attempted to recruit scientists from the Soviet program to work on their biological weapon programs. It is entirely possible that nations or terrorist organizations that strive for biological weapons might have stocks of smallpox from Russia or elsewhere. Further, the recent discovery at the NIH implies that samples taken when the virus was still endemic within human populations could still be viable today. Smallpox was studied in laboratories worldwide during the eradication effort, and it's impossible to conclusively say that no other sources of viable smallpox exist.
In addition to samples maintained (knowingly or unknowingly) in a laboratory setting, it is also possible that viable Variola still exists in the environment. Smallpox DNA has been detected in corpses that have been mummified and buried in coffins, and in corpses unearthed from permafrost graves. DNA has also been recently detected in scabs from individuals that had been infected or vaccinated using a close cousin of smallpox, vaccinia virus, from over 100 years ago. Fortunately none of these examples have contained viable smallpox, only DNA remnants from the infection. However, just like laboratory samples, it is possible that environmental sources could provide another reservoir for infectious smallpox.
For these reasons, there can be no question about our maintenance and continued study of smallpox both here in the United States and in Russia. As demonstrated by the FDA and NIH, errors in smallpox inventory and sample storage have occurred in the past. It is entirely possible that other stocks of smallpox, either known or unknown, still exist at locations not in Atlanta or Novosibirsk. The rise and evolution of synthetic biology also poses risks, as the genome of Variola is public knowledge and the construction of a synthetic smallpox virus becomes a possibility. The study of smallpox needs to continue, as an effective antiviral and more effective vaccines would limit the risks posed by a reintroduction of smallpox into humans. The only way this research can continue is to maintain and study the stocks of virus held by the CDC and VECTOR and continue to fund efforts to develop effective antiviral drugs and vaccines against smallpox.
Andy Kilianski is a National Research Council Postdoctoral Fellow in the BioSciences Division at Edgewood Chemical and Biological Center. These statements are the opinion of the author alone and do not necessarily represent the views of the National Academy of Science or the Department of Defense. He can be reached at firstname.lastname@example.org.
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