2015-09-23-世界卫生组织-Recommended_composition_of_influenza_virus_vaccines_for_use_in_the_2016_southern_hemisphere_influenza_season_8页_144kb

Summary of the 2016 Southern Hemisphere Influenza Vaccine Recommendations

Core Content

This document outlines the recommended composition of influenza vaccines for the 2016 southern hemisphere influenza season, based on the analysis of seasonal influenza activity, antigenic and genetic characteristics, and antiviral drug resistance data from February to September 2015.

Main Points

1. Influenza Activity in 2015-2016 Season

• Influenza activity was reported in all major regions: Africa, the Americas, Asia, Europe, and Oceania.
• Activity varied from sporadic to widespread, with A(H1N1)pdm09, A(H3N2), and B viruses circulating.
• In the northern hemisphere, high activity was observed from February to April, with a decline from April onwards.
• In the southern hemisphere, activity remained low until May, after which some countries reported moderate to high levels.
• A(H1N1)pdm09 activity was widespread in Asia, Europe, and parts of Africa, with sporadic cases in other regions.
• A(H3N2) activity was generally moderate to high in the Americas, Asia, Europe, and Oceania.
• Influenza B activity was variable, with B/Yamagata/16/88 lineage viruses predominant in many countries, and a shift to B/Victoria/2/87 lineage in Australia and New Zealand from June to August 2015.

2. Zoonotic Influenza Infections

• A(H5N6) and A(H5N1) viruses were reported in China, Egypt, and Indonesia.
• No sustained human-to-human transmission was observed.
• A(H7N9) infections were reported in China, with some mild cases in Bangladesh and Egypt.
• A(H1N1)v and A(H3N2)v viruses were reported in the United States, with one fatal case.

3. Antigenic and Genetic Characteristics

• A(H1N1)pdm09 viruses were antigenically homogeneous and closely related to the vaccine strain A/California/7/2009.
• Most A(H1N1)pdm09 viruses belonged to genetic clade 6B, which is continuing to diversify.
• A(H3N2) viruses fell into clades 3C.2 and 3C.3, with 3C.2a being predominant globally.
• Antigenic differences were observed between 3C.2a and 3C.3a viruses, though both were inhibited by ferret antisera raised against A/Hong Kong/4801/2014 and A/Switzerland/9715293/2013 viruses.
• Influenza B viruses of the B/Victoria/2/87 and B/Yamagata/16/88 lineages co-circulated, with B/Yamagata/16/88 dominant in most countries. In Australia and New Zealand, B/Victoria/2/87 lineage viruses became predominant by August 2015.
• B/Yamagata/16/88 lineage viruses were mostly sensitive to neuraminidase inhibitors, but some showed reduced sensitivity due to specific substitutions (e.g., D197N, I221T).
• All B/Victoria-like viruses were sensitive to neuraminidase inhibitors, except for three that showed reduced peramivir inhibition.

4. Antiviral Drug Resistance

• Neuraminidase inhibitors: Most A(H1N1)pdm09 and A(H3N2) viruses were sensitive, with some showing reduced inhibition due to substitutions (e.g., H275Y, R292K, S331R, Q136K, D197N, I221T, H273Y, T146I, D432G, N151T).
• M2 inhibitors: Almost all A(H1N1)pdm09 and A(H3N2) viruses had the S31N substitution in the M2 protein, which confers resistance to amantadine and rimantadine.

5. Vaccine Composition Recommendations

• Trivalent vaccines for the 2016 southern hemisphere season should include:
  • An A/California/7/2009 (H1N1)pdm09-like virus.
  • An A/Hong Kong/4801/2014 (H3N2)-like virus.
  • A B/Brisbane/60/2008-like virus.
• Quadrivalent vaccines should include the above three viruses plus a B/Phuket/3073/2013-like virus.

6. Vaccine Development and Resources

• Candidate vaccine viruses and reagents for vaccine standardization are available on the WHO website.
• Reference viruses can be obtained from the following WHO Collaborating Centres and Essential Regulatory Laboratories:
  • WHO CC Melbourne (Dr Ian Barr): Shareholdings in CSL Limited.
  • WHO CC Atlanta, WHO CC Beijing, WHO CC London, WHO CC Memphis, WHO CC and ERL NIID Tokyo, WHO ERL CBER Bethesda, WHO ERL NIBSC London, WHO ERL TGA Canberra.
• Dr Barr was allowed to continue as an adviser after agreeing to refrain from acquiring additional shares in vaccine manufacturing companies.

Key Information

• The WHO recommends influenza vaccine compositions for the southern hemisphere based on global surveillance data.
• The 2016 southern hemisphere vaccine includes A/California/7/2009 (H1N1)pdm09, A/Hong Kong/4801/2014 (H3N2), and B/Brisbane/60/2008 for trivalent vaccines, with the addition of B/Phuket/3073/2013 for quadrivalent vaccines.
• Antigenic and genetic analysis showed that the majority of circulating viruses were antigenically related to the recommended vaccine strains.
• Antiviral resistance data indicates that neuraminidase inhibitors remain effective, though some substitutions in the neuraminidase gene may reduce their efficacy.
• Surveillance data and vaccine candidate information are updated on the WHO Global Influenza Programme website.

References

• WHO conducts technical consultations in February and September to recommend vaccine strains.
• Additional information on influenza activity, vaccine candidates, and antiviral resistance is available on the WHO website: http://www.who.int/influenza/vaccines/virus/recommendations/201509_influenzaactivitytable.pdf
• Vaccine reagents and candidate viruses can be obtained from:
  • Immunobiology, Office of Laboratories, TGA, Australia
  • NIBSC, UK
  • FDA, USA
  • NIID, Japan
• WHO has published guidelines on the prevention of influenza: http://www.who.int/influenza/guidelines/en/