| Influenza (flu) |
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Since 1999, the World Health Organization (WHO) has issued annual recommendations for influenza vaccine formulations. One reformulation of the influenza vaccine is for the Northern Hemisphere, and the other is for the Southern Hemisphere. Both recommendations are trivalent, i.e. featuring three strains.
Since the 2012–13 season, the WHO recommendations have also included the formulation of an annual quadrivalent vaccine, featuring an additional B-strain.
Northern hemisphere recommended strains
The following is a list of WHO recommended strains for the Northern Hemisphere influenza season. Starting in the 2012–2013 season, the recommendation shifted from a trivalent influenza vaccine (TIV) containing three strains to a quadrivalent influenza vaccine (QIV) that contains both influenza B lineages.
| NH winter season | Influenza A H1N1 | Influenza A H3N2 | Influenza B Victoria | Influenza B Yamagata |
|---|---|---|---|---|
| November 1998–April 1999 | A/Beijing/262/95 (H1N1)-like virus | A/Sydney/5/97 (H3N2)-like virus | N/A | B/Beijing/184/93-like virus |
| November 1999–April 2000 | A/Beijing/262/95 (H1N1)-like virus | A/Sydney/5/97 (H3N2)-like virus | B/Shangdong/7/97-like virus | B/Beijing/184/93-like virus |
| 2000–2001 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | N/A | B/Beijing/184/93-like virus |
| 2001–2002 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | N/A | B/Sichuan/379/99-like virus |
| 2002–2003 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | B/Hong Kong/330/2001-like virus | N/A |
| 2003–2004 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | B/Hong Kong/330/2001-like virus | N/A |
| 2004–2005 | A/New Caledonia/20/99 (H1N1)-like virus | A/Fujian/411/2002 (H3N2)-like virus | N/A | B/Shanghai/361/2002-like virus |
| 2005–2006 | A/New Caledonia/20/99 (H1N1)-like virus | A/California/7/2004 (H3N2)-like virus | N/A | B/Shanghai/361/2002-like virus |
| 2006–2007 | A/New Caledonia/20/99 (H1N1)-like | A/Wisconsin/67/2005 (H3N2)-like virus | B/Malaysia/2506/2004-like virus | N/A |
| 2007–2008 | A/Solomon Islands/3/2006 (H1N1)-like virus | A/Wisconsin/67/2005 (H3N2)-like virus | B/Malaysia/2506/2004-like virus | N/A |
| 2008–2009 | A/Brisbane/59/2007 (H1N1)-like virus | A/Brisbane/10/2007 (H3N2)-like virus | N/A | B/Florida/4/2006-like virus |
| 2009–2010 | A/Brisbane/59/2007 (H1N1)-like virus | A/Brisbane/10/2007 (H3N2)-like virus | B/Brisbane/60/2008-like virus | N/A |
| 2010–2011 | A/California/7/2009 (H1N1)-like virus | A/Perth/16/2009 (H3N2)-like virus | B/Brisbane/60/2008-like virus | N/A |
| 2011–2012 | A/California/7/2009 (H1N1)-like virus | A/Perth/16/2009 (H3N2)-like virus | B/Brisbane/60/2008-like virus | N/A |
| 2012–2013 | A/California/7/2009 (H1N1)pdm09-like virus | A/Victoria/361/2011 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Wisconsin/1/2010-like virus |
| 2013–2014 | A/California/7/2009 (H1N1)pdm09-like virus | A(H3N2) virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011 | B/Brisbane/60/2008-like virus | B/Massachusetts/2/2012-like virus |
| 2014–2015 | A/California/7/2009 (H1N1)pdm09-like virus | A/Texas/50/2012 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Massachusetts/2/2012-like virus |
| 2015–2016 | A/California/7/2009 (H1N1)pdm09-like virus | A/Switzerland/9715293/2013 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Phuket/3073/2013-like virus |
| 2016–2017 | A/California/7/2009 (H1N1)pdm09-like virus | A/Hong Kong/4801/2014 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Phuket/3073/2013-like virus |
| 2017–2018 | A/Michigan/45/2015 (H1N1)pdm09-like virus | A/Hong Kong/4801/2014 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Phuket/3073/2013-like virus |
| 2018–2019 | A/Michigan/45/2015 (H1N1)pdm09-like virus | A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus | B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage) | B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage) |
| 2019–2020 | A/Brisbane/02/2018 (H1N1)pdm09-like virus | A/Kansas/14/2017 (H3N2)-like virus | B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage) | B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage) |
| 2020–2021 egg-based vaccines | A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus | A/Hong Kong/2671/2019 (H3N2)-like virus | B/Washington/02/2019 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2020–2021 cell- or recombinant-based vaccines | A/Hawaii/70/2019 (H1N1)pdm09-like virus | A/Hong Kong/45/2019 (H3N2)-like virus | B/Washington/02/2019 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2021–2022 egg-based vaccines | A/Victoria/2570/2019 (H1N1)pdm09-like virus | A/Cambodia/e0826360/2020 (H3N2)-like virus | B/Washington/02/2019 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2021–2022 cell- or recombinant-based vaccines | A/Wisconsin/588/2019 (H1N1)pdm09-like virus | A/Cambodia/e0826360/2020 (H3N2)-like virus | B/Washington/02/2019 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2022–2023 egg-based vaccines | A/Victoria/2570/2019 (H1N1)pdm09-like virus | A/Darwin/9/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2022–2023 cell- or recombinant-based vaccines | A/Wisconsin/588/2019 (H1N1)pdm09-like virus | A/Darwin/6/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2023–2024 egg-based vaccines | A/Victoria/4897/2022 (H1N1)pdm09-like virus | A/Darwin/9/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2023–2024 cell- or recombinant-based vaccines | A/Wisconsin/67/2022 (H1N1)pdm09-like virus | A/Darwin/6/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
Southern hemisphere recommended strains
The following is a list of WHO recommended strains for the southern hemisphere influenza season.
| SH winter season | Influenza A H1N1 | Influenza A H3N2 | Influenza B Victoria | Influenza B Yamagata |
|---|---|---|---|---|
| 1999 | A/Beijing/262/95 (H1N1)-like virus | A/Sydney/5/97 (H3N2)-like virus | N/A | B/Beijing/184/93-like virus |
| May–October 2000 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | B/Shangdong/7/97-like virus | B/Beijing/184/93-like virus |
| May–October 2001 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | N/A | B/Sichuan/379/99-like virus |
| 2002 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | N/A | B/Sichuan/379/99-like virus |
| 2003 | A/New Caledonia/20/99 (H1N1)-like virus | A/Moscow/10/99 (H3N2)-like virus | B/Hong Kong/330/2001-like virus | N/A |
| 2004 | A/New Caledonia/20/99 (H1N1)-like virus | A/Fujian/411/2002 (H3N2) - like virus | B/Hong Kong/330/2001-like virus | N/A |
| 2005 | A/New Caledonia/20/99 (H1N1)-like virus | A/Wellington/1/2004 (H3N2)-like virus | N/A | B/Shanghai/361/2002-like virus |
| 2006 | A/New Caledonia/20/99 (H1N1)-like virus | A/California/7/2004 (H3N2)-like virus | B/Malaysia/2506/2004-like virus | N/A |
| 2007 | A/New Caledonia/20/99 (H1N1)-like | A/Wisconsin/67/2005 (H3N2)-like virus | B/Malaysia/2506/2004-like virus | N/A |
| 2008 | A/Solomon Islands/3/2006 (H1N1)-like virus | A/Brisbane/10/2007 (H3N2)-like virus | N/A | B/Florida/4/2006-like virus |
| 2009 | A/Brisbane/59/2007 (H1N1)-like virus | A/Brisbane/10/2007 (H3N2)-like virus | N/A | B/Florida/4/2006-like virus |
| 2010 | A/California/7/2009 (H1N1)-like virus | A/Perth/16/2009 (H3N2)-like virus | B/Brisbane/60/2008-like virus | N/A |
| 2011 | A/California/7/2009 (H1N1)-like virus | A/Perth/16/2009 (H3N2)-like virus | B/Brisbane/60/2008-like virus | N/A |
| 2012 | A/California/7/2009 (H1N1)pdm09-like virus | A/Perth/16/2009 (H3N2)-like virus | B/Brisbane/60/2008-like virus | N/A |
| 2013 | A/California/7/2009 (H1N1)pdm09-like virus | A/Victoria/361/2011 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Wisconsin/1/2010-like virus |
| 2014 | A/California/7/2009 (H1N1)pdm09-like virus | A/Texas/50/2012 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Massachusetts/2/2012-like virus |
| 2015 | A/California/7/2009 (H1N1)pdm09-like virus | A/Switzerland/9715293/2013 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Phuket/3073/2013-like virus |
| 2016 | A/California/7/2009 (H1N1)pdm09-like virus | A/Hong Kong/4801/2014 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Phuket/3073/2013-like virus |
| 2017 | A/Michigan/45/2015 (H1N1)pdm09-like virus | A/Hong Kong/4801/2014 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Phuket/3073/2013-like virus |
| 2018 | A/Michigan/45/2015 (H1N1)pdm09-like virus | A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus | B/Brisbane/60/2008-like virus | B/Phuket/3073/2013-like virus |
| 2019 | A/Michigan/45/2015 (H1N1)pdm09-like virus | A/Switzerland/8060/2017 (H3N2)-like virus | B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage) | B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage) |
| 2020 | A/Brisbane/02/2018 (H1N1)pdm09-like virus | A/South Australia/34/2019 (H3N2)-like virus | B/Washington/02/2019-like (B/Victoria lineage) virus | B/Phuket/3073/2013-like (B/Yamagata lineage) virus |
| 2021 egg-based vaccines | A/Victoria/2570/2019 (H1N1)pdm09-like virus | A/Hong Kong/2671/2019 (H3N2)-like virus | B/Washington/02/2019 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2021 cell- or recombinant-based vaccines | A/Wisconsin/588/2019 (H1N1)pdm09-like virus | A/Hong Kong/45/2019 (H3N2)-like virus | B/Washington/02/2019 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2022 egg-based vaccines | A/Victoria/2570/2019 (H1N1)pdm09-like virus | A/Darwin/9/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2022 cell- or recombinant-based vaccines | A/Wisconsin/588/2019 (H1N1)pdm09-like virus | A/Darwin/6/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2023 egg-based vaccines | A/Sydney/5/2021 (H1N1)pdm09-like virus | A/Darwin/9/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |
| 2023 cell- or recombinant-based vaccines | A/Sydney/5/2021 (H1N1)pdm09-like virus | A/Darwin/6/2021 (H3N2)-like virus | B/Austria/1359417/2021 (B/Victoria lineage)-like virus | B/Phuket/3073/2013 (B/Yamagata lineage)-like virus |