An estimated 0.8 percent of people with certain primary immune deficiency diseases (PIDs) excrete poliovirus for prolonged periods after receiving oral polio vaccine, according to a study led by The Task Force for Global Health that appeared in the June 13 issue of Frontiers in Immunology.
With eradication of wild poliovirus expected soon, increasing attention is now being focused on addressing other potential sources of infection, including vaccine-derived poliovirus that can spread and cause paralytic disease similar to wild poliovirus.
In the study, researchers examined stool samples of 635 people with PIDs in 13 countries who had received oral polio vaccine. They found a total of five patients or 0.8 percent who excreted virus for a prolonged period or more than six months.
“The whole world is going through a process of containing everything that could represent a source of polio infections,” said Mark McKinlay, PhD, director of the Center for Vaccine Equity at The Task Force. “With this new study, we have a better understanding of the frequency that patients with immune deficiencies are excreting poliovirus for prolonged periods.”
In response to the findings, The Task Force was asked to convene a meeting in June of polio eradication partners, including the World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), and Bill & Melinda Gates Foundation, to discuss a strategy to identify and ultimately treating people with PIDS who are identified as poliovirus excretors.
The group agreed that an expanded and focused surveillance effort will be needed and could start as soon as 2018. McKinlay said, however, that treating this population will be more challenging.
The Task Force has been working with a company called ViroDefense Inc. on development of two polio antiviral compounds that can stop excretion of vaccine-derived poliovirus, thereby reducing the risks of paralysis and transmission. “Our goal is to make these antivirals available on a compassionate use basis by the end of 2018,” he said. “But there are significant regulatory issues that must be addressed before these compounds can be made widely available around the world.”
The Task Force will continue to support WHO and CDC as they map out the surveillance and treatment strategy.
The Task Force has been involved in polio eradication since 1988. In addition to helping address the issue of vaccine-derived poliovirus in people with PIDs, The Task Force is providing support to the U.S. government in certifying successful containment of poliovirus in U.S. laboratories. From 2013-16, The Task Force also supported the global introduction of inactivated polio vaccine and the switch to a safer oral polio vaccine.
Read more about The Task Force’s work to eradicate polio: