Skip to Main Content

A strategy devised to keep the world polio-free once the virus has finally been wiped from the Earth may be setting the Global Polio Eradication Initiative on a collision course with scientists studying a range of other viruses.

Non-polio scientists — specifically those who study diarrheal and respiratory diseases — have collections of research specimens stashed around the world that could actually harbor hidden polioviruses. The global polio plan calls for such specimens to be destroyed or sent to one of a small number of facilities designated as safe to house polio specimens.


That means scientists who focus on infections such as rotavirus, influenza, or measles may be asked to sacrifice research collections representing years of work for the sake of the polio cause. Some have been less than enthusiastic when queried about their specimen collections.

“They didn’t even reply,” Michel Zaffran, the World Health Organization’s point person for polio eradication, told STAT.

Others have reacted negatively, insisting the polio program cannot ask unrelated scientific fields to destroy research specimens. “The tricky point is most of these laboratories will not want to destroy their specimens because these represent a large investment, many years of study,” Zaffran said.

These specimens may pose a risk to a post-polio world because people infected with polio (most of whom show no symptoms) and children given the oral vaccine (which contains live, but weakened, polioviruses) emit the viruses in their stool for a time after infection or immunization. Stool samples are often collected and stored by scientists studying other infections.


The vaccine viruses can regain the power to paralyze, which is why specimens that might include them are also on the list for containment. If vaccine viruses escape from a lab and start circulating among unprotected children, they can do as much damage as regular polioviruses.

Respiratory specimens — swabs coated with mucus from the throat or lungs — are also potentially problematic because early in polio infection the virus can be found in tonsils and the adenoid glands.

And the risk isn’t purely theoretical. Some of the techniques used to work on specimens for measles research, for instance, would allow hidden polioviruses to grow and multiply.

The polio eradication campaign is now realizing it didn’t do enough work over the years to get non-polio scientists on board with the need for destruction or containment of research specimens that might contain polioviruses, Zaffran admitted.

In fact, some scientists whose work could be affected may not yet know about the plan.

Richard Webby is the director of a WHO collaborating center for studies of influenza. He knew the polio program was looking to find out which researchers have specimen collections that might be of concern, but did not know there were plans to destroy specimens that might contain hidden polioviruses.

Webby, who is based at St. Jude Children’s Research Hospital in Memphis, said he hasn’t heard any complaints from within the influenza research community, but thinks that may be because scientists aren’t yet aware of what may be at stake.

According to Nicoletta Previsani, the WHO’s coordinator for poliovirus containment, the global polio plan is now working on a compromise: Materials deemed to be at low risk of containing polioviruses will require no further action; high-risk specimens should be seriously considered for destruction; and specimens considered to be at medium risk may need to undergo a case-by-case assessment of how to minimize the risk.

“Polioviruses do pose risks, and therefore the more we get rid of them … the better it is for everybody.”

Nicoletta Previsani, World Health Organization

Efforts are underway to help all parties assess the likelihood that specimen collections might contain polioviruses. The polio program recently held a meeting on the issue in London, inviting representatives of laboratory networks whose members study viruses that infect the human gastrointestinal and respiratory tracts.

Working on the proposed compromise is helping to draw some reluctant scientists into the discussion, Previsani said: “I think we all live on the same planet, and we all see and realize that [polio] eradication is a common public health good.”

“When you start really discussing about why these requirements have been put in place instead of imposing them,” she added, “then any rational person would understand and share the perspective that yes, indeed, those polioviruses do pose risks, and therefore the more we get rid of them and the more we appropriately confine them, the better it is for everybody.”

The Global Polio Eradication Initiative is a consortium of the WHO, Rotary International, the US Centers for Disease Control and Prevention, the United Nations Children’s Fund, and the Bill and Melinda Gates Foundation.

The containment effort has ramped up in recent months after type 2 polioviruses were declared eradicated in September of last year. (There were originally three strains of polio. Type 3 is believe to be gone as well, leaving only type 1; it now circulates in only two countries, Pakistan and Afghanistan.)

Countries that use oral polio vaccine recently stopped administering the version containing the type 2 component in a massive international exercise known as “the switch.”

The Global Action Plan, which charts the final steps to be taken to get to eradication of all polio, called for the type 2 virus containment work to be completed by the end of July, but there is no hope now that deadline can be met. “This is much more complex than was originally anticipated when the plan was drawn,” Zaffran said.

The goal of the plan is to make sure, once polioviruses no longer circulate in nature, that viruses in laboratories and vaccine production facilities don’t escape and undo decades of work to get rid of polio. The polio campaign began in 1988 and has cost more than $14 billion to date.

Some specimens are inherently riskier than others. Recent stool collections from a place like the United States — where polio has been vanquished for decades and where the oral vaccine was phased out more than 15 years ago — would be of little concern.

But stool samples collected in India would be problematic. Though that country stopped polio transmission in 2012, the oral vaccine is used there still and stool samples could teem with vaccine viruses.

Dr. Neal Halsey, a vaccine expert at Johns Hopkins Bloomberg School of Public Health who studies polio and many other infectious viruses, said he culled his specimen collections a few years back in anticipation of the day the polio campaign would ask him to do so.

But Halsey is nearing retirement. He knows other scientists would find this an unwelcome request. “There are lots of us in the infectious disease and public health community who have conducted these studies over the years,” he said.

Some will argue against destruction of holdings that are part of an ongoing study, one in which patients agreed to give a stool specimen. “It would be unethical for those samples to be destroyed before that question can be answered,” said Dr. William Petri Jr., who works on polio and other diseases that infect the gastric tract at the University of Virginia School of Medicine.

Petri does understand the risk posed by stored specimens, though, and thinks collections that are being held onto just in case should be safely discarded.

Still, these kinds of collections can be tremendously useful, which is why scientists save them. New testing techniques allow scientists to find important information in old specimens.

For instance, Halsey and colleagues did some research on Guillain-Barré syndrome in Guatemala a few years back and kept the blood samples they drew at the time. Now, they’re going back to see if they can find Zika virus in those specimens, which could provide evidence that Zika arrived in the Americas even earlier than is currently thought.

“Had we not saved those specimens, we wouldn’t be able to test for that,” Halsey said.

Laboratories have safety procedures in place and their work is scrutinized to see that they follow them. But accidents do happen. And pathogens have on occasion escaped from labs.

The last person to die from smallpox — in 1978 — was a British medical photographer infected when a laboratory located below her office mishandled the virus and it spread, likely through the building’s air ducts. And in 1977, a decades-old version of the H1N1 flu virus, which at that point had not circulated since 1957, reemerged and caused a large global outbreak among young people.

Still, even the people trying to persuade non-polio scientists to give up their potentially problematic collections recognize the Global Polio Eradication Initiative may have bitten off more than it can chew.

“Where do we really draw the line?” wondered Olen Kew, a longtime polio researcher who recently retired from the CDC and is the containment coordinator for the United States. “You’ve got to kind of get the sweet spot between being too strict and not being strict enough.”

An earlier version of this story incorrectly stated that the polio eradication campaign has cost more than $11 billion. It has cost more than $14 billion.