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Global Health

Questions and Answers about Poliovirus Containment

This webpage includes answers to questions that U.S. laboratories and other facilities may have about poliovirus containment.

Containment Basics

What is poliovirus containment?

Poliovirus containment is a system of safety requirements and procedures developed to minimize the risks of accidental releases of poliovirus into the community from laboratories or other facilities that handle or store this virus.

Containment is a key objective of the Polio Eradication and Endgame Strategic Plan 2013-2018. The containment requirements and procedures are described in the WHO Global Action Plan to minimize poliovirus facility-associated risk after type-specific eradication of wild polioviruses and sequential cessation of oral polio vaccine use (GAPIII [2MB, 232 pages]).

Why must poliovirus be contained?

The world is closer than ever to eradicating polio. Wild poliovirus type 2 (WPV2) was eradicated in 1999, and the last case of WPV type 3 occurred in Nigeria in 2012. WPV type 1 circulates in only three countries (Pakistan, Afghanistan, and Nigeria).

Laboratories and other facilities that handle or store poliovirus materials represent the largest remaining risk for accidental reintroduction of the virus into communities to again cause paralysis and death. It’s critical that these laboratories and facilities follow containment requirements and procedures to minimize this risk.

Even in countries with high polio vaccination coverage, some individuals and groups may not be vaccinated or fully protected against polio, putting them at risk of getting disease if they are exposed.

Which poliovirus materials are subject to containment now?

All poliovirus type 2 (PV2) materials, including WPV2, vaccine-derived poliovirus type 2 (VDPV2), and Sabin type 2-related poliovirus, are subject to containment. This includes:

  • infectious poliovirus materials, including laboratory strains and clinical isolates, and
  • potentially infectious materials, such as stool or respiratory specimens that may contain poliovirus.

Laboratories and other facilities in the United States are encouraged to also contain poliovirus types 1 and 3 materials if they are not currently using or planning to use these materials for crucial research or other essential work.

What are VDPVs, and why are they subject to containment?

VDPVs are genetically divergent strains of Sabin oral polio vaccine (OPV) that behave more like WPVs. Therefore, VDPVs can more easily spread to unvaccinated people who come in contact with the stool or respiratory secretions of an infected person. VDPVs may cause illness, including paralytic poliomyelitis.

For containment purposes, VPDVs are treated as WPVs. VDPVs have caused large polio outbreaks due to circulating VPDVs (cVDPVs) in places with low poliovirus vaccination coverage. Other VDPVs called immunodeficiency-associated VDPVs (iVDPVs) have infected patients with defects in antibody production, resulting in infections that last many years. There is no evidence of people with iVDPV spreading the virus to others. Also, iVDPVs do not appear to be precursors of cVDPV outbreaks. Only a few of approximately 100 known people with iVDPV (excretors) since 1961 are alive today or continue to shed poliovirus. Antiviral treatment is currently being developed.

Why is it important to contain PV2 materials now?

WPV2 was eradicated in 1999. Since then, all polio cases associated with PV2 have been caused by OPV directly (vaccine-associated paralytic polio [VAPP]) or by VDPV2 from inadequate vaccine coverage with trivalent OPV (tOPV), which contains poliovirus types 1, 2, and 3. Due to continued occurrence of VAPP and outbreaks and chronic infections associated with VDPV2, WHO decided to discontinue all routine OPV2/Sabin2 use after May 1, 2016, by switching from tOPV to bOPV (containing only types 1 and 3) along with the introduction of inactivated polio vaccine (IPV).

With the removal of all live PV2 virus from the vaccine, laboratories and other facilities that handle or store poliovirus materials represent the largest remaining risk for accidental reintroduction of PV2 into communities to again cause paralysis and death. It’s critical that these laboratories and facilities follow containment requirements and procedures to minimize this risk.

What if poliovirus is released into the community?

If poliovirus is accidently released into the community, it could lead to a resurgence of polio, especially in areas with low vaccination coverage. A lesson regarding the need for containment is the 1978 accidental release of smallpox virus from a laboratory in the United Kingdom, resulting in a person dying from the disease. This triggered countries to further reduce the number of facilities retaining smallpox virus to the two official repositories that remain today.

Containment requirements and procedures

What are the poliovirus containment requirements and procedures?

The poliovirus containment requirements and procedures are described in GAPIII [2MB, 232 pages].

The basic steps are:

Identify:

All countries must conduct a survey of all their laboratories and other facilities to identify infectious or potentially infectious poliovirus materials, and develop a national inventory of laboratories and facilities that handle or store these materials.

Destroy:

All countries must request that laboratories and other facilities destroy all unneeded poliovirus materials. It is expected that many facilities worldwide will destroy poliovirus materials.

Transfer:

Laboratories and other facilities may choose to transfer needed poliovirus materials to designated poliovirus-essential facilities.

Contain:

Countries may choose to designate poliovirus-essential facilities that will continue to work with needed poliovirus materials according to the requirements described in GAPIII. It is expected that only a limited number of facilities worldwide will be designated as poliovirus-essential facilities.

In each country:

  • designated poliovirus-essential facilities should implement Annex 2 or 3 of the GAPIII
  • other laboratories and facilities that are likely to investigate new poliovirus cases should implement a non-retention policy for poliovirus and implement Annex 6 of the GAPIII

National authorities for containment should apply the WHO GAPIII Containment Certification Scheme and certify poliovirus-essential facilities against the GAPIII requirements in coordination with WHO. Certified poliovirus-essential facilities will need to maintain GAPIII requirements and be regularly reassessed.

In the Region of the Americas, each country submits a report of their national inventory, destruction, and designation of poliovirus-essential facilities to WHO through their Regional Certification Commission.

What is the global community doing to address concerns about GAPIII requirements?

WHO is convening groups of experts to support poliovirus containment activities. For more information, see Containment Supporting Groups.

What is a poliovirus-essential facility?

A poliovirus-essential facility is a facility that maintains the ability to work with infectious and potentially infectious PV2 materials. These facilities follow the containment requirements described in GAPIII [2MB, 232 pages]. Such facilities serve critical national and international functions (such as vaccine production, vaccine testing, public health and virologic research, and diagnostics, including virus isolation from clinical specimens and environmental samples, and serologic studies). For additional information about poliovirus-essential facilities, see GAPIII [2MB, 232 pages].

Guidance for non-polio laboratories is being developed.

What biosafety levels does GAPIII specify for poliovirus-essential facilities?

GAPIII specifies that poliovirus-essential facilities holding PV2 materials will follow the requirements in Annex 2 or 3 with a mandatory shower-out requirement. Although not formally aligned with traditional biosafety levels, these requirements are most similar to BSL-3 with additional biosecurity conditions. The mandatory shower-out requirement is currently under review.

Where can poliovirus-essential facilities holding WPV materials find technical guidance?

Please refer to Annex 2 of GAPIII [2MB, 232 pages].

Where can poliovirus-essential facilities holding OPV/Sabin materials find technical guidance?

Please refer to Annex 3 of GAPIII [2MB, 232 pages].

How can a U.S. laboratory obtain information on becoming a poliovirus-essential facility?

Please send an email to the National Poliovirus Containment Coordinator (NPCC).

Where can laboratories find technical guidance for handling diagnostic materials from potential polio cases?

Please refer to Annex 6 of GAPIII [2MB, 232 pages].

Where can laboratories find technical guidance for destroying and transferring poliovirus materials?

Poliovirus infectivity is rapidly destroyed by autoclaving. For questions about destroying and transferring poliovirus materials, please send an email to the National Poliovirus Containment Coordinator (NPCC).

Containment in the U.S.

What is the U.S. National Poliovirus Containment Program?

The U.S. National Poliovirus Containment Program (NPVCP) is responsible for conducting the survey and inventory of laboratories and other facilities in the United States that may hold poliovirus materials, and to provide technical assistance in completing the survey and providing guidance on polio containment to these laboratories and facilities.

This program is led by the National Poliovirus Containment Coordinator (NPCC), who is based in Atlanta. The NPCC reports to CDC, the National Certification Committee (NCC), and the Office of the Assistant Secretary of Health (OASH), through the National Vaccine Program Office (NVPO) in the Department of Health and Human Services. The NCC, after confirming the validity of the reports, submits these to the Pan American Health Organization (PAHO) and the Regional Certification Commission (RCC).

What is the United States currently doing for poliovirus containment?

Since October 2015, the U.S. government has been working alongside other national governments to implement the requirements and procedures described in GAPIII [2MB, 232 pages] to contain infectious and potentially infectious PV2 materials in laboratories and other facilities.

In December 2015, the NPVCP started a survey of laboratories and other facilities in the United States to obtain information about the infectious and potentially infectious poliovirus types 1, 2, and 3 materials they are currently using or storing, and their plans for containment.

This survey is based on the findings of a previous survey from 2002 to 2003, which showed that 122 out of 105,356 laboratories in 32,429 institutions reported that they stored WPV infectious or potentially infectious materials. Twelve of the 122 laboratories were at CDC.

Which laboratories and facilities are being surveyed?

The NPVCP is surveying:

  • 149 laboratories at CDC, and
  • more than 200 laboratories at federal facilities, academic institutions, state and large local health departments, industrial facilities, commercial diagnostic laboratories, and hospitals identified through the 2002-2003 survey and other ways, such as literature reviews.

The NPVCP distributed the survey to laboratories based on estimated risk:

  • First priority: hold WPV2/VDPV2 infectious materials
  • Second priority: hold WPV2/VDPV2 potentially infectious materials
  • Third priority: hold OPV2/Sabin 2 infectious materials
  • Fourth priority: hold OPV/Sabin potentially infectious materials

For potentially infectious poliovirus materials, NPVCP assigned the highest risk to stool specimens.

How many laboratories have completed the survey so far?

By March 2016, all 149 CDC laboratories had completed the survey. As of September 2016, 179 other U.S. laboratories and facilities have completed the survey.

The NPVCP continues to encourage U.S. laboratories and facilities to complete the survey. It is critical that any remaining U.S. laboratories and facilities complete this survey to support national and international poliovirus containment activities.

Which PV2 materials do the laboratories and facilities have?

As of September 2016, CDC laboratories and other U.S. laboratories and facilities contain the following infectious and potentially infectious PV2 materials:

Poliovirus Type 2 Material CDC Laboratories Other U.S. Laboratories and Facilities
Infectious
WPV2 6 17
OPV2 7 15
Potentially infectious
WPV2 9 10
OPV2 10 11

Have laboratories in the United States destroyed or transferred poliovirus materials?

Yes. The CDC Polio Laboratory has destroyed nearly 190,000 vials of infectious or potentially infectious poliovirus materials. The NPVCP is aware of other U.S. laboratories and facilities that are destroying or transferring known poliovirus infectious materials

All WPV2 and VDPV2 at CDC are now being contained within the CDC Polio Laboratory.

How many laboratories in the United States are likely to be designated poliovirus-essential facilities?

Possibly 10 laboratories in the United States, including the CDC Poliovirus Laboratory with the largest poliovirus collection in the world, are likely to be designated poliovirus-essential facilities.

Do other, non-virology laboratories with specimens that may contain poliovirus need to follow the requirements in GAPIII?

Yes. Stool and respiratory specimens and sewage samples collected for other microbiological and non-microbiological studies may contain poliovirus and are subject to containment requirements described in GAPIII.

Which respiratory and stool specimens are considered potentially infectious materials?

According to GAPIII requirements, respiratory* and stool specimens, including RNA extracts*, are considered potentially infectious materials if they were collected at a time or place where WPV2 was circulating or tOPV was given to the population.

These potentially infectious materials, especially stool specimens, may be found in laboratories, including virology, microbiology, and parasitology, whose staff may currently be less aware of the poliovirus containment requirements and procedures. This, for example, may include laboratories conducting work on viral or bacterial gastroenteritis and hepatitis, or laboratories studying the human microbiome.

*The application of this requirement is currently under review.

Are full-length cDNA clones of poliovirus genomes considered potentially infectious materials?

Yes. According to GAPIII requirements, full-length cDNA clones of poliovirus genomes are potentially infectious materials. Guidelines for these materials are currently under review.

How will containment be validated in poliovirus essential facilities?

The WHO’s Containment Certification Scheme [47 pages] includes site visit audits of candidate poliovirus-essential facilities to validate containment. Audits of candidate poliovirus-essential facilities in the United States will begin after 2016.

How will containment of poliovirus be confirmed?

National level: The NPCC will prepare reports to the National Polio Certification Committee (NCC) based on the results of the survey and audits of candidate poliovirus-essential facilities. The facilities will be audited by the National Authority for Containment and issued containment certificates.

WHO regional level: The U.S. NCC will prepare a report, at least annually, to the Regional Polio Certification Commission, describing steps taken to ensure poliovirus containment and other measures to maintain polio-free status in the United States.

Global level: The Global Commission for the Certification of the Eradication of Poliomyelitis (GCC) will confirm that global containment of poliovirus has been achieved and maintained. Global certification of polio eradication is dependent upon appropriate progress toward global poliovirus containment.

For additional information, see

Global Containment

What progress has been made globally for poliovirus containment?

See information and updates on global polio containment.

Global switch to bivalent OPV

What is “the switch”?

In April 2016, WHO globally discontinued all use of tOPV, containing Sabin types 1, 2, and 3, and replaced this vaccine with bivalent OPV (bOPV), which contains Sabin types 1 and 3.

For more information and updates about the global switch from tOPV to bOPV, visit WHO’s webpage Immunizations, Vaccines, and Biologicals.

Does “the switch” affect the U.S. polio vaccination program?

No. Since 2000, the United States has only used IPV.

Why is “the switch” important?

The poliovirus type 2 component of OPV accounts for 40% of VAPP cases, and more than 90% of recent circulating vaccine-derived poliovirus (cVDPV) cases. In addition, WPV2 has not been detected anywhere since 1999, and the GCC declared this serotype globally eradicated in September 2015. Switching from tOPV to bOPV is a crucial part of the polio endgame strategy, in order to prevent VAPP and cVDPVs cases.

Laboratories and other facilities than handle or store PV2 materials represent the largest remaining risk for accidental reintroduction of the virus into communities to again cause paralysis and death. It’s critical that these laboratories and facilities follow containment requirements and procedures to minimize this risk.

Why was “the switch” done in 2016?

The switch was scheduled at the earliest time when all the prerequisites could be met, including stopping persistent cVDPV2 outbreaks, declaring WPV2 eradicated, introducing IPV, and containing PV2. In October 2015, the WHO Strategic Advisory Group of Experts (SAGE) on Immunization recommended that the switch proceed as scheduled.

Resources

Where can I get more information?

Containment

Polio eradication

Polio

Contact us

How can I reach the National Poliovirus Containment Program?

You can send your questions or comments to poliocontainment@cdc.gov.

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