2023-01-04-世界卫生组织-Influenza_at_the_human-animal_interface_summary_and_assessment,_5_January_2023_5页_223kb

Influenza at the Human-Animal Interface: Summary and Risk Assessment (12 Nov 2022 - 5 Jan 2023)

Overview

During the period from 12 November 2022 to 5 January 2023, WHO received official notifications of:

• One human case of influenza A(H5N6) virus infection (China).
• Three human cases of influenza A(H9N2) virus infection (all from China).
• One human case of influenza A(H1N2) variant virus infection (Taiwan, China).

Risk Assessment: The overall public health risk from known influenza viruses at the human-animal interface has not changed since the last assessment on 11 November 2022. The likelihood of sustained human-to-human transmission remains low for these viruses. Human infections are expected where the viruses circulate in animal populations. All new influenza A virus subtypes are required to be reported under IHR (2005).

Detailed Risk Assessment by Virus Type

Avian Influenza A(H5) Viruses

• Current Situation: One confirmed human H5N6 case from China (November 2022). A(H5) viruses (including H5N1) continue to circulate widely in birds globally, with Europe experiencing a large epidemic.
• Risk Assessment:
  1. More human cases of A(H5) infection are anticipated due to ongoing viral circulation in birds.
  2. Sustained human-to-human transmission remains unlikely.
  3. Travelers from affected areas could transmit H5 viruses during international travel, but community-level spread is unlikely due to limited transmissibility.
  4. Note: A specific rapid assessment for A(H5N1) clade 2.3.4.4b viruses is available.

Avian Influenza A(H9N2) Viruses

• Current Situation: Three human H9N2 cases from China (November 2022).
• Risk Assessment:
  1. More human cases of H9N2 infection are anticipated due to the virus's circulation in poultry.
  2. Sustained human-to-human transmission remains unlikely.
  3. Travelers from affected areas could potentially transmit H9N2, but community-level spread is unlikely.

Swine Influenza Viruses

• Current Situation: One confirmed human infection with influenza A(H1N2)v virus in Taiwan (December 2022).
• Risk Assessment:
  1. More human cases of swine influenza are anticipated due to ongoing viral circulation in pigs.
  2. Sustained human-to-human transmission remains unlikely.
  3. Travelers from affected areas could potentially transmit swine influenza viruses, but community-level spread is unlikely.

Overall Risk Management Recommendations

1. No special traveler screening or entry restrictions recommended for current influenza viruses at the human-animal interface.
2. Travelers to areas with animal influenza outbreaks should avoid contact with birds and pigs, practice good hand hygiene, and follow food safety/hygiene.
3. General public advised to avoid contact with sick or dead birds.
4. Global surveillance is stressed due to the evolving nature of influenza viruses, requiring vigilance and collaboration between animal and human health sectors.
5. Reporting of new influenza virus subtypes under IHR (2005) is mandatory; labs should follow specific guidelines.
6. Viruses with pandemic potential should be shared promptly with WHO's Global Influenza Surveillance and Response System (GISRS).
7. Actions not required at this time regarding the current COVID-19 pandemic situation.
8. The WHO Pandemic Influenza Preparedness (PIP) Framework facilitates virus sharing for pandemic risk assessment and vaccine development.