Poliovirus Containment: An Integral Part of Polio Eradication
As the world works to eradicate polio, we must take precautions to minimize the risk of eradicated polioviruses being released from the laboratories and facilities that retain them.
Why It Matters
Poliovirus can affect the central nervous system, resulting in paralysis and death. The last case resulting from wild poliovirus type 2 occurred in 1999 and the virus was formally declared eradicated in 2015. Even with its eradication, wild poliovirus type 2 continues to be used for research and development:
- Laboratories use poliovirus to conduct important research for cancer treatment and other life-saving work
- Manufacturers use live poliovirus to make vaccine to prevent new cases of polio from occurring around the globe
- Laboratories conduct research for other diseases using potentially infectious materials, such as stool or respiratory samples. These samples may have been collected in regions where wild poliovirus was circulating or where the live oral poliovirus vaccine was in use.
4 Pillars of Poliovirus Containment
- Identify: All countries survey their laboratories and other facilities to identify infectious and potentially infectious poliovirus materials
- Destroy: All countries request that laboratories and facilities destroy all unneeded poliovirus materials
- Transfer: Laboratories and facilities may choose to transfer needed poliovirus materials to designated poliovirus-essential facilities
- Contain: Countries will designate poliovirus-essential facilities for continued work with poliovirus type 2. These facilities are expected to comply with the World Health Organization Global Action Plan requirements.
CDC has a long history in the fight against poliovirus worldwide. The agency provides technical assistance for poliovirus outbreak response, laboratory testing, disease surveillance, vaccination campaign planning, program monitoring and evaluation, and research. This expertise in poliovirus is combined with CDC’s expertise in oversight and monitoring of biosafety and security in the laboratory to support U.S. and global poliovirus containment efforts.
Poliovirus Containment is Necessary to Ensure Polio Stays Eradicated
Poliovirus containment is a key objective of the World Health Organization’s Global Polio Eradication Initiative. Facilities designated as “poliovirus-essential” must follow defined poliovirus containment measures to minimize the risk that the virus could get into the environment and cause harm.
At this time, poliovirus containment is only focused on poliovirus type 2. There are three kinds of poliovirus type 2 that need to be contained:
- Wild poliovirus type 2: Although eradicated, samples of wild poliovirus type 2 still remain in laboratories and vaccine manufacturing facilities.
- Vaccine-derived poliovirus type 2: Rarely, the strain of poliovirus in the oral vaccine can mutate to a form of poliovirus that can cause paralysis and circulate like wild poliovirus.
- Oral poliovirus vaccine type 2: This weakened strain of poliovirus does not cause disease, and protects against infection with wild poliovirus, but is no longer used for routine immunization anywhere in the world.
Vaccinating People Against Poliovirus is Still Important
Oral polio vaccine (OPV) is still used in many countries. In April 2016, the world switched from trivalent OPV, which included poliovirus types 1, 2, and 3, to bivalent OPV, which only includes poliovirus types 1 and 3.
In the United States, only inactivated poliovirus vaccine (IPV) is used, and over 90% of the population is vaccinated against poliovirus. IPV still contains all three types of poliovirus and one dose is recommended in all countries that use bivalent OPV.