2012-02-22-世界卫生组织-Recommended_composition_of_influenza_virus_vaccines_for_use_in_the_2012-2013_northern_hemisphere_influenza_season_16页_631kb

Summary of Influenza Virus Vaccine Composition for the 2012-2013 Northern Hemisphere Influenza Season

Core Content

This document outlines the recommended composition of influenza virus vaccines for the 2012-2013 northern hemisphere influenza season. It provides an overview of global influenza activity, antigenic and genetic characteristics of circulating viruses, and their resistance to antiviral drugs. It also details the results of serology studies and the final vaccine recommendations.

Influenza Activity Overview (September 2011 – January 2012)

• Global Activity: Influenza activity was reported in Africa, the Americas, Asia, Europe, and Oceania, with varying levels of circulation.
• Influenza A(H1N1)pdm09: Circulated at very low levels globally, except for some countries in Asia and the Americas.
• Influenza A(H3N2): Predominant in Europe, many countries in the Americas and northern Africa, and some countries in Asia. Widespread activity was reported in Japan in January 2012.
• Influenza B: Circulated in many parts of the world and predominated in some countries. In China, B/Victoria/2/87 lineage viruses were dominant, while B/Yamagata/16/88 lineage viruses increased in prevalence.

Antigenic and Genetic Characteristics

Influenza A(H1N1)pdm09

• All detected A(H1N1) viruses were A(H1N1)pdm09.
• Antigenically homogeneous and closely related to the vaccine virus A/California/7/2009.
• Genetic diversity was observed with at least eight genetic groups, though most were antigenically indistinguishable.
• A small proportion showed reduced reactivity with A/California/7/2009-like reference viruses, associated with HA amino acid changes at positions 153-157.

Influenza A(H3N2)

• Antigenically heterogeneous, with many viruses closely related to A/Perth/16/2009 (vaccine virus for 2011-2012 season).
• An increasing proportion showed reduced reactivity with A/Perth/16/2009 antisera.
• Higher reactivity was observed with A/Victoria/361/2011-like reference viruses.
• Genetic groups included A/Victoria/361/2011 (group 3) and A/Brisbane/299/2011 (group 6), with the majority in group 3.

Influenza B

• Two lineages circulated: B/Victoria/2/87 and B/Yamagata/16/88.
• B/Yamagata/16/88 lineage viruses showed higher reactivity with post-infection ferret antisera against B/Wisconsin/1/2010-like and other recent reference viruses compared to B/Florida/4/2006.
• B/Victoria/2/87 lineage viruses were closely related to the vaccine virus B/Brisbane/60/2008.
• HA genes of most B viruses were in genetic clade 3.

Resistance to Antiviral Drugs

Neuraminidase Inhibitors

• Most A(H1N1)pdm09 viruses were sensitive to oseltamivir.
• A small number of oseltamivir-resistant A(H1N1)pdm09 viruses were reported, due to H275Y substitution in neuraminidase.
• All A(H3N2) and B viruses tested were sensitive to oseltamivir and zanamivir.
• Peramivir and laninamivir susceptibility was also confirmed.

M2 Inhibitors

• A(H1N1)pdm09 and A(H3N2) viruses were resistant to M2 inhibitors (amantadine and rimantadine) due to S31N substitution in M2 protein.
• One A(H3N2) exception was noted.

Vaccine Composition Recommendations

• Recommended Viruses:

  • An A/California/7/2009 (H1N1)pdm09-like virus
  • An A/Victoria/361/2011 (H3N2)-like virus
  • A B/Wisconsin/1/2010-like virus

• Alternative Option:

  • For those using a B/Victoria/2/87 lineage vaccine virus in trivalent or quadrivalent vaccines, B/Brisbane/60/2008-like viruses are still appropriate.

Additional Information

• Vaccine Approval: National or regional authorities approve vaccine compositions.

• WHO Recommendations: WHO provides guidelines for influenza prevention.

• Candidate Vaccine Viruses and Reagents: Available on WHO website and from specific institutions:

  • Immunobiology, Office of Laboratory and Scientific Services, Therapeutic Goods Administration, Australia
  • Division of Virology, National Institute for Biological Standards and Control, UK
  • Center for Biologics Evaluation and Research, Food and Drug Administration, USA
  • Center for Influenza Virus Research, National Institute of Infectious Diseases, Japan

• Reference Viruses: Requests should be directed to WHO Collaborating Centres:

  • WHO Collaborating Centre for Reference and Research on Influenza, VIDRL, Australia
  • WHO Collaborating Centre for Reference and Research on Influenza, National Institute of Infectious Diseases, Japan
  • WHO Collaborating Centre for Surveillance, Epidemiology and Control of Influenza, CDC, USA
  • WHO Collaborating Centre for Reference and Research on Influenza, MRC National Institute for Medical Research, UK
  • WHO Collaborating Centre for Reference and Research on Influenza, China CDC, China

Zoonotic Influenza Infections

• A(H5N1): 21 confirmed human cases, 15 fatal, reported from Cambodia, China, Egypt, Indonesia, and Viet Nam.
• A(H3N2)v: 8 confirmed cases in the USA, including A(H3N2)v, A(H1N1)v, and A(H1N2)v.
• A(H9N2): No human cases reported during the period.

Annex 1: Global Influenza Activity Summary

• Detailed influenza activity by region and country from September 2011 to January 2012 is summarized in Annex 1.
• The table includes data on the prevalence of different influenza subtypes and lineages in various regions.

Conclusion

The document emphasizes the importance of updating vaccine composition based on circulating influenza strains, including the inclusion of A/California/7/2009 (H1N1)pdm09, A/Victoria/361/2011 (H3N2), and B/Wisconsin/1/2010-like viruses for the 2012-2013 season. It also highlights the need for continued surveillance and monitoring of influenza activity and vaccine effectiveness.