2003-12-31-世界卫生组织-WHO_global_action_plan_for_laboratory_containment_of_wild_polioviruses_49页_230kb

WHO Global Action Plan for Laboratory Containment of Wild Polioviruses (Second Edition)

Core Content

This document outlines the WHO Global Action Plan for Laboratory Containment of Wild Polioviruses, aiming to minimize the risk of reintroducing wild polioviruses from laboratories to the community. It is a critical component of the global effort to eradicate poliomyelitis, especially in the context of transitioning from oral polio vaccine (OPV) to inactivated polio vaccine (IPV) and ensuring long-term biosafety.

Main Purpose

The plan seeks to:

• Ensure that laboratory facilities and biosafety practices are consistent with the risk of inadvertent transmission of poliovirus to the community.
• Provide a systematic global strategy to contain wild poliovirus (WPV) and vaccine-derived polioviruses (VDPVs).
• Guide countries through three distinct phases of containment: Laboratory Survey and Inventory, Global Certification, and Post Global Certification.

Key Definitions

Polioviruses

• Belong to the Enterovirus genus and have three serotypes (1, 2, 3).
• Infection occurs via the PVR:CD155 receptor.
• Wild polioviruses are those that have circulated in the community and reference strains derived from them.
• VDPVs are classified as wild for containment and programmatic purposes due to their potential to cause paralysis.

Infectious Materials

• Wild poliovirus infectious materials include clinical and environmental samples (e.g., faeces, throat swabs, sewage) and laboratory products derived from them.
• Potential wild poliovirus infectious materials refer to materials with unknown origin or uncertain status that may contain wild polioviruses, especially faecal and respiratory samples from endemic areas.

Main Viewpoints

1. Poliovirus Transmission and Survival:

   • Poliovirus is transmitted through droplets or faecal-oral route.
   • It can survive in the environment for extended periods, especially in sewage, soil, and water.
   • It is resistant to common disinfectants but is rapidly inactivated by heat, formaldehyde, bleach, and UV light.

2. Rationale for Containment:

   • Even with high levels of immunity, lab accidents can lead to poliovirus transmission.
   • The 1977 smallpox containment incident highlights the importance of biosafety in preventing laboratory-borne outbreaks.
   • VAPP (vaccine-associated paralytic poliomyelitis) and VDPVs pose ongoing risks due to genetic changes and continued transmission in under-immunized populations.

3. Phases of Containment:

   • Phase I (Laboratory Survey and Inventory):
     • Conduct surveys to identify and destroy unused materials.
     • Develop national inventories and report to regional certification commissions.
     • Implement BSL-2/polio biosafety measures.
     • Prepare for global certification.
   • Phase II (Global Certification):
     • Begin when no wild poliovirus is isolated for one year.
     • Notify laboratories of transmission interruption.
     • Choose containment options: inactivate/destroy materials, transfer to appropriate labs, or implement BSL-2/polio or BSL-3/polio measures.
     • Document containment for global certification.
   • Phase III (Post Global Certification):
     • After global certification, if OPV use is stopped, containment requirements for both WPV and Sabin strains become more stringent.
     • A third edition of the plan is expected to address post-certification biosafety requirements.

Key Information

• Wild polioviruses can persist in the community and are not fully eradicated even with current immunization efforts.
• VDPVs are a growing concern due to genetic mutations and potential for re-emergence.
• Biosafety levels (BSL-2/polio and BSL-3/polio) are defined based on risk assessment and containment needs.
• Global certification is a three-year process requiring documented absence of WPV transmission.
• Post-certification will involve more stringent containment if OPV is discontinued.
• IPV production from WPV is still in development and requires special biosafety protocols.

Conclusion

The WHO Global Action Plan emphasizes the importance of biosafety in laboratories to prevent the reintroduction of wild polioviruses. It outlines a phased approach to containment, ensuring that laboratory practices align with the goals of polio eradication. The plan also highlights the need for ongoing vigilance even after certification, as VDPVs and residual WPV may still pose a risk. Continued international cooperation, compliance with biosafety standards, and adaptation to changing immunization policies are essential to achieving a polio-free world.