2013-02-20-世界卫生组织-Recommended_composition_of_influenza_virus_vaccines_for_use_in_the_2013-2014_northern_hemisphere_influenza_season_21页_225kb

Summary of Influenza Virus Vaccine Composition for the 2013-2014 Northern Hemisphere Influenza Season

Core Content

The World Health Organization (WHO) recommends the composition of influenza vaccines for the 2013-2014 northern hemisphere influenza season based on the analysis of global influenza activity and antigenic and genetic characteristics of circulating viruses. This recommendation is made in February, with a follow-up in September for the southern hemisphere.

Main Influenza Activity in the Northern Hemisphere (September 2012 – January 2013)

• Influenza A(H1N1)pdm09: Circulated at low levels globally, with outbreaks reported in some countries in Africa, Asia, Central and South America, and Europe. Most were antigenically similar to the A/California/7/2009 vaccine strain.
• Influenza A(H3N2): Predominant in North America, some parts of Asia, and early in Europe. These viruses were antigenically and genetically similar to A/Victoria/361/2011 and A/Texas/50/2012. However, ferret antisera raised against egg-propagated A/Victoria/361/2011 showed reduced reactivity against cell-propagated viruses.
• Influenza B viruses: Circulated widely and were predominant in some countries. The B/Victoria/2/87 lineage remained prevalent in certain regions, while the B/Yamagata/16/88 lineage increased in proportion and became dominant in many areas.

Antigenic and Genetic Characteristics

• A(H1N1)pdm09: Most viruses remained antigenically homogeneous and closely related to A/California/7/2009. Viruses in clades 6 and 7 shared the S185T and S451N changes in HA.
• A(H3N2): Most recent viruses were antigenically similar to A/Victoria/361/2011 and A/Texas/50/2012. Viruses in clade 3C showed amino acid substitutions such as T128A, R142G, and N145S.
• Influenza B:
  • B/Victoria/2/87 lineage viruses were closely related to B/Brisbane/60/2008.
  • B/Yamagata/16/88 lineage viruses were mostly in clade 2, except in China where they were in clade 3.
  • B/Yamagata/16/88 viruses were antigenically distinguishable from the previous vaccine strain B/Wisconsin/1/2010.

Antiviral Drug Resistance

• Neuraminidase inhibitors: Most A(H1N1)pdm09 and all A(H3N2) and B viruses were sensitive to oseltamivir and zanamivir. Resistance to oseltamivir was due to the H275Y substitution in the neuraminidase gene.
• M2 inhibitors: All A(H1N1)pdm09 and A(H3N2) viruses, except one, had the S31N substitution in the M2 protein, conferring resistance to amantadine and rimantadine.

Vaccine Composition Recommendations

• Trivalent vaccines should include:

  • A/California/7/2009 (H1N1)pdm09-like virus
  • A(H3N2) virus antigenically similar to A/Victoria/361/2011 or A/Texas/50/2012 (due to antigenic changes in earlier vaccine strains)
  • B/Massachusetts/2/2012-like virus (B/Yamagata/16/88 lineage)

• Quadrivalent vaccines should include the above three viruses plus:

  • B/Brisbane/60/2008-like virus (B/Victoria/2/87 lineage)

Key Information

• The recommended vaccine strains are based on global surveillance and antigenic analysis.
• The WHO recommends the use of A/Texas/50/2012 as the A(H3N2) component due to antigenic changes in A/Victoria/361/2011-like viruses.
• Vaccine manufacturers and national authorities determine the final vaccine formulation and approval.
• WHO provides resources for vaccine standardization, including candidate vaccine viruses and reagents, on its website.
• Specific laboratories and centers are designated for influenza surveillance and vaccine development.

Declarations of Interest

• All WHO Collaborating Centres (CCs) and Essential Regulatory Laboratories (ERLs) were required to declare any personal or financial interests.
• Dr Anne Kelso (WHO CC Melbourne) had significant shareholdings in CSL but agreed to refrain from acquiring additional shares.
• Dr Othmar Engelhardt (WHO ERL London) had travel expenses related to a conference but was determined not to conflict with the consultation objectives.
• Both Dr Kelso and Dr Engelhardt participated in the consultation as Advisers.

Additional Resources

• Candidate vaccine viruses and reagents can be obtained from:

  • Immunobiology, Office of Laboratory and Scientific Services, Australia
  • National Institute for Biological Standards and Control, UK
  • Center for Biologics Evaluation and Research, USA
  • National Institute of Infectious Diseases, Japan

• Reference viruses should be requested from:

  • WHO Collaborating Centre for Reference and Research on Influenza, Australia
  • WHO Collaborating Centre for Reference and Research on Influenza, Japan
  • WHO Collaborating Centre for Surveillance, Epidemiology and Control of Influenza, USA
  • WHO Collaborating Centre for Reference and Research on Influenza, UK
  • WHO Collaborating Centre for Reference and Research on Influenza, China

• Influenza surveillance information is updated on the WHO website.

Annex 2 Summary

Annex 2 provides a detailed summary of the extent and type of influenza activity across different regions and months (August 2012 – January 2013), indicating the prevalence of A(H1N1)pdm09, A(H3N2), and B viruses in various countries. The data show varying levels of activity, with some regions reporting outbreaks of multiple virus types.