Lab-stored smallpox: A deadly virus we may still need

In 1977 the disease was eradicated. Only two known research collections of smallpox virus remain, in laboratories in Russia and the United States.

This month, the World Health Organisation is debating whether to set a date for destroying these remaining research samples. Elimination of the virus collections is a bad idea.

Smallpox, the most infamous infectious disease in history, killed 300 million to 500 million people in the 20th century alone — more than three times the number killed by wars. Its eradication was the culmination of an 11-year global campaign that stands as a milestone in cooperative international action.

So why not exterminate the last lab specimens? The reasons are born of 21st century changes in global security, technology, politics and, particularly, the threat of bioterrorism. Smallpox is a potential weapon because of the disease’s high fatality rate (30 to 40 per cent), its ability to pass from person to person, and the fact that over 40 per cent of the world’s population has no immunity because civilian vaccination was stopped over 30 years ago.

In 1980, nearly three years after the last natural cases of smallpox occurred, WHO urged countries to destroy all remaining virus samples or transfer them to the secure Russian or American repositories. However, there was no attempt to verify that labs or governments complied with this request. As a result, it has long been suspected that there are infectious smallpox samples held by other labs in a number of countries — either clandestine specimens or samples unknowingly retained in large virus collections in lab freezers.

In addition, modern biology has created methods that can retrieve virus intact from frozen corpses, old lab specimens, or other materials. And advances in molecular biology make it possible to synthesise smallpox DNA from published information and then use the DNA to rebuild the smallpox virus.

In this light, destruction of the two known virus collections will not eradicate the possibility of smallpox on earth. It will, however, eradicate much of our ongoing public health research with the virus. We think that is very undesirable.

The US has stockpiled over 300 million doses of an effective smallpox vaccine — enough for every American. But this low-tech vaccine is not ideal for all people and can itself cause deaths. Moreover, most other countries have little or no smallpox vaccine of any kind, and there are no drugs or effective and safer high-tech vaccines licensed to treat the disease should it occur in the unvaccinated. Under these conditions, most of the world’s population could be held hostage to terrorists wielding the virus.

Genetic sequencing

Continuing research on smallpox will further develop the tools to detect, defend and respond to an attack. Research on the live virus is ongoing and includes the genetic sequencing of the many strains of virus, development of new methods for rapid field diagnosis, creation of new and safer vaccines, and early development of first-ever drug treatments for smallpox. Recently, the Institute of Medicine and two expert committees at the WHO have reported on continuing public health advances that are being developed with research on live smallpox virus.

If we were to exterminate the remaining research virus now, we could potentially rebuild it from genetic material should we need it to develop additional drugs or vaccines. But that would put us on a course to undercut an international norm, which we support, that prohibits synthesis or genetic manipulation of smallpox virus. This proposition has been accepted by all 193 WHO member governments, including the United States. Terrorists, however, have no such constraints against synthetic biology, for example by changing an animal pox virus into human smallpox.

Alternatively, we could wait until after an attack to restart this research, but that would leave us without adequate preparation or expertise.

Some argue that the greatest threat from smallpox would come from the misuse or theft of the strains in the Russian and US repositories. But that is a very remote possibility, because of the extremely tight security at both labs, and because WHO oversees all research with these samples.

We believe that it is better to accept this tiny risk of terrorist theft or researcher malfeasance than to deny ourselves capabilities to defend against smallpox recurring from any source.

Smallpox, the naturally occurring disease, is gone. But let us be sure that when we eventually destroy the last of the legitimate research samples, we have adequate defenses to deal with any recurrence of smallpox, from clandestine sources or from virus created in a terrorist’s laboratory.

We have an obligation to ensure that our children’s children never have to worry about seeing this ancient scourge kill yet again. Destroying the remaining research specimens of smallpox at this time will prevent us from fulfiling this obligation.