Who issues annual recommendations for influenza vaccine formulations, and since when?

Since 1999, the World Health Organization (WHO) has been issuing annual recommendations for the formulations of influenza vaccines. These recommendations are crucial for guiding the production of vaccines to target the most prevalent strains of the influenza virus each year.

How many distinct recommendations for influenza vaccine formulations does the WHO issue annually?

The WHO issues two distinct recommendations annually for influenza vaccine formulations. One recommendation is tailored for the Northern Hemisphere, and the other is for the Southern Hemisphere, reflecting the different timing of influenza seasons in these regions.

What was the typical composition of influenza vaccines recommended by the WHO prior to the 2012-2013 season?

Prior to the 2012-2013 season, the WHO's recommendations for influenza vaccines were typically trivalent, meaning they included three strains of the influenza virus: one Influenza A H1N1 strain, one Influenza A H3N2 strain, and one Influenza B strain.

When did the WHO begin recommending quadrivalent influenza vaccine formulations?

Starting with the 2012-2013 season, the WHO's recommendations began to include the formulation of an annual quadrivalent influenza vaccine (QIV). This quadrivalent vaccine contains an additional strain of the Influenza B virus, specifically from the B/Yamagata lineage, in addition to the three strains typically found in trivalent vaccines.

What has been the impact of non-pharmaceutical interventions during the COVID-19 pandemic on influenza B lineages?

Due to the widespread use of non-pharmaceutical interventions (like masking and social distancing) during the COVID-19 pandemic, the B/Yamagata influenza lineage has not been isolated since March 2020. This has led to speculation that this lineage may have been eradicated.

Which influenza B lineage has been removed from WHO and regulatory body recommendations starting with the 2024 Southern Hemisphere season?

The B/Yamagata influenza lineage has been removed from the influenza vaccine recommendations by the WHO and other regulatory bodies starting with the 2024 Southern Hemisphere influenza season. This decision follows the lack of isolation of this lineage since March 2020.

What Influenza A strain was recommended for the Northern Hemisphere during the 1998-1999 season?

For the 1998-1999 Northern Hemisphere influenza season, the WHO recommended an Influenza A H1N1 strain similar to A/Beijing/262/95 and an Influenza A H3N2 strain similar to A/Sydney/5/97.

Which Influenza B strains were recommended for the Northern Hemisphere during the 1999-2000 season?

For the 1999-2000 Northern Hemisphere season, the WHO recommended an Influenza B strain similar to B/Shangdong/7/97 and an Influenza B strain similar to B/Beijing/184/93. This indicates a period where both B lineages might have been considered.

What were the recommended Influenza A strains for the Northern Hemisphere from 2000 to 2002?

For the Northern Hemisphere seasons of 2000-2001 and 2001-2002, the WHO recommended Influenza A H1N1 strains similar to A/New Caledonia/20/99 and Influenza A H3N2 strains similar to A/Moscow/10/99.

Which Influenza B strains were recommended for the Northern Hemisphere during the 2002-2004 seasons?

During the 2002-2003 and 2003-2004 Northern Hemisphere influenza seasons, the recommended Influenza B strain was similar to B/Hong Kong/330/2001. The B/Yamagata lineage was not included in the recommendations for these specific seasons.

What Influenza A strains were recommended for the Northern Hemisphere in the 2004-2005 season?

For the 2004-2005 Northern Hemisphere influenza season, the recommended strains were an Influenza A H1N1 similar to A/New Caledonia/20/99 and an Influenza A H3N2 similar to A/Fujian/411/2002. The Influenza B strain recommended was similar to B/Shanghai/361/2002.

What was the recommended Influenza A H1N1 strain for the Northern Hemisphere from 2006 to 2008?

For the Northern Hemisphere influenza seasons of 2006-2007 and 2007-2008, the recommended Influenza A H1N1 strain was similar to A/New Caledonia/20/99. In the 2007-2008 season, it was updated to be similar to A/Solomon Islands/3/2006.

What change occurred in the recommended H1N1 strain for the Northern Hemisphere starting with the 2009-2010 season?

For the 2009-2010 Northern Hemisphere season, the recommended Influenza A H1N1 strain was similar to A/Brisbane/59/2007. This strain was also recommended for the subsequent 2010-2011 season.

What is the significance of the '(H1N1)pdm09' nomenclature mentioned in the vaccine recommendations?

The '(H1N1)pdm09' nomenclature refers to the strain of the 2009 pandemic H1N1 influenza virus. It is a newer way of naming this specific strain and does not indicate a different virus from the one previously referred to as A/California/7/2009-like.

What Influenza A H3N2 strain was recommended for the Northern Hemisphere in the 2013-2014 season, and why was it changed?

For the 2013-2014 Northern Hemisphere season, the recommended Influenza A H3N2 strain was similar to A/Victoria/361/2011. However, the recommendation for the following season (2014-2015) shifted to A/Texas/50/2012, because antigenic changes were observed in earlier A/Victoria/361/2011-like vaccine viruses due to adaptation for egg propagation.

Which Influenza B strains were recommended for the Northern Hemisphere in the 2018-2019 season?

For the 2018-2019 Northern Hemisphere influenza season, the WHO recommended an Influenza B strain similar to B/Colorado/06/2017 (belonging to the B/Victoria lineage) and an Influenza B strain similar to B/Phuket/3073/2013 (belonging to the B/Yamagata lineage).

What were the recommended strains for Northern Hemisphere egg-based vaccines in the 2020-2021 season?

For the 2020-2021 Northern Hemisphere season, egg-based vaccines were recommended to include an Influenza A H1N1 strain similar to A/Guangdong-Maonan/SWL1536/2019, an Influenza A H3N2 strain similar to A/Hong Kong/2671/2019, a B/Victoria lineage strain similar to B/Washington/02/2019, and a B/Yamagata lineage strain similar to B/Phuket/3073/2013.

What Influenza A H3N2 strain was recommended for the Northern Hemisphere in the 2022-2023 season?

For the 2022-2023 Northern Hemisphere influenza season, the recommended Influenza A H3N2 strain was similar to A/Darwin/9/2021 for egg-based vaccines and similar to A/Darwin/6/2021 for cell- or recombinant-based vaccines.

What Influenza A H1N1 strain was recommended for the Northern Hemisphere in the 2023-2024 season?

For the 2023-2024 Northern Hemisphere influenza season, the recommended Influenza A H1N1 strain was similar to A/Victoria/4897/2022 for egg-based vaccines and similar to A/Wisconsin/67/2022 for cell- or recombinant-based vaccines.

What Influenza A H3N2 strain is recommended for the Northern Hemisphere in the 2024-2025 season?

For the 2024-2025 Northern Hemisphere influenza season, the WHO recommends an Influenza A H3N2 strain similar to A/Thailand/8/2022 for egg-based vaccines and similar to A/Massachusetts/18/2022 for cell- or recombinant-based vaccines.

What Influenza A strains were recommended for the Southern Hemisphere during the 1999-2000 season?

For the 1999-2000 Southern Hemisphere influenza season, the WHO recommended an Influenza A H1N1 strain similar to A/New Caledonia/20/99 and an Influenza A H3N2 strain similar to A/Moscow/10/99.

Which Influenza B strains were recommended for the Southern Hemisphere in the 2000-2001 and 2001-2002 seasons?

For the 2000-2001 Southern Hemisphere season, the recommended Influenza B strain was similar to B/Beijing/184/93. For the 2001-2002 season, the recommendation changed to a strain similar to B/Sichuan/379/99.

What Influenza A H3N2 strain was recommended for the Southern Hemisphere in the 2004-2005 season?

For the 2004-2005 Southern Hemisphere influenza season, the recommended Influenza A H3N2 strain was similar to A/Fujian/411/2002, alongside an Influenza A H1N1 strain similar to A/New Caledonia/20/99 and an Influenza B strain similar to B/Shanghai/361/2002.

What was the recommended Influenza A H1N1 strain for the Southern Hemisphere from 2010 to 2012?

For the Southern Hemisphere influenza seasons of 2010 and 2011, the recommended Influenza A H1N1 strain was similar to A/California/7/2009. For the 2012 season, the same strain, now referred to as A/California/7/2009 (H1N1)pdm09-like virus, was recommended.

What change occurred in the recommended H3N2 strain for the Southern Hemisphere between the 2011-2012 and 2012-2013 seasons?

For the 2011-2012 Southern Hemisphere season, the recommended Influenza A H3N2 strain was similar to A/Perth/16/2009. For the 2012-2013 season, this was updated to a strain similar to A/Victoria/361/2011.

Which Influenza B strains were recommended for the Southern Hemisphere in the 2018-2019 season?

For the 2018-2019 Southern Hemisphere influenza season, the WHO recommended an Influenza B strain similar to B/Colorado/06/2017 (B/Victoria lineage) and an Influenza B strain similar to B/Phuket/3073/2013 (B/Yamagata lineage).

What Influenza A H1N1 strain was recommended for the Southern Hemisphere in the 2023-2024 season?

For the 2023-2024 Southern Hemisphere influenza season, the recommended Influenza A H1N1 strain was similar to A/Sydney/5/2021 for both egg-based and cell- or recombinant-based vaccines.

What Influenza A H3N2 strain was recommended for the Southern Hemisphere in the 2024-2025 season?

For the 2024-2025 Southern Hemisphere influenza season, the recommended Influenza A H3N2 strain was similar to A/Thailand/8/2022 for egg-based vaccines and similar to A/Massachusetts/18/2022 for cell- or recombinant-based vaccines.

What is the significance of the note stating 'N/A' in the vaccine strain tables?

The 'N/A' (Not Applicable) entries in the vaccine strain tables indicate that a specific lineage of Influenza B virus was not included in the WHO's recommendations for that particular hemisphere and season. For example, the B/Victoria lineage was often marked as 'N/A' in earlier Southern Hemisphere recommendations.

What does the note regarding A/Texas/50/2012 and A/Victoria/361/2011 explain?

The note explains that A/Texas/50/2012 was recommended as the Influenza A H3N2 vaccine component for certain seasons because it maintained antigenic properties similar to recently circulating viruses like A/Victoria/361/2011, even after adaptation to egg propagation, which can sometimes alter virus characteristics.

What does the note about the B/Yamagata lineage being excluded from recommendations signify?

The note signifies that the WHO, FDA, and EMA have advised against including the B/Yamagata lineage in influenza vaccines because it is no longer considered necessary. This is due to the lineage not being isolated since March 2020, suggesting it may no longer be circulating widely or has been eradicated.

How has the approach to recommending Influenza B strains evolved since the 1999-2000 season?

Initially, recommendations sometimes included strains from both B/Victoria and B/Yamagata lineages, or only one lineage. Since the 2012-2013 season, quadrivalent vaccines, including both lineages, became part of the recommendations. More recently, with the lack of B/Yamagata isolation, recommendations are shifting away from including this lineage.

What is the primary reason for the annual reformulation of influenza vaccines?

Influenza viruses, particularly Influenza A and B, are known to change or 'drift' over time. Annual reformulation of vaccines is necessary to ensure they target the specific strains of influenza viruses that are predicted to be most common and cause illness during the upcoming flu season, thereby maximizing vaccine effectiveness.

What is the role of the World Health Organization (WHO) in the influenza vaccine formulation process?

The WHO plays a central role by convening experts twice a year to review global influenza surveillance data. Based on this data, they issue recommendations for the virus strains that should be included in the influenza vaccines for the upcoming Northern and Southern Hemisphere seasons.

What does the term 'like-virus' or '-like virus' signify in the context of vaccine strain recommendations?

The term '-like virus' or 'like-virus' indicates that the recommended vaccine strain is antigenically similar to the named virus. This means it shares key surface proteins (like hemagglutinin and neuraminidase) that the immune system recognizes, even if it's not the exact same isolate.

How do cell- or recombinant-based vaccines differ in strain recommendations compared to egg-based vaccines?

While often similar, there can be slight differences in the specific virus strains recommended for cell- or recombinant-based vaccines compared to egg-based vaccines in a given season. These differences arise from the different methods of virus propagation and the specific strains that adapt best to each production method, as seen in the 2020-2021 Northern Hemisphere recommendations.

What is the historical trend regarding the inclusion of both Influenza B lineages in vaccine recommendations?

Historically, recommendations sometimes included only one Influenza B lineage (e.g., B/Victoria or B/Yamagata). However, since the 2012-2013 season, quadrivalent vaccines, which include both lineages, have been recommended, reflecting the circulation of both. The future inclusion of the B/Yamagata lineage is now uncertain due to its lack of recent isolation.

What specific Influenza A H1N1 strain replaced A/California/7/2009 in the recommendations, and why?

The A/California/7/2009 strain was replaced in recommendations starting around the 2016-2017 season with strains like A/Michigan/45/2015. This change was made to improve protection against emerging subclades of H1N1 that had developed over the preceding seasons.

What is the significance of the 'See also' section in relation to vaccine reformulations?

The 'See also' section lists related topics such as 'Flu season', 'Influenza evolution', 'Influenza research', and 'Influenza-like illness'. These are relevant because the effectiveness and need for vaccine reformulation are directly tied to the ongoing evolution of the influenza virus and the patterns of flu seasons.

What does the term 'trivalent' refer to in the context of influenza vaccines?

Trivalent refers to an influenza vaccine that contains antigens from three different influenza virus strains. Typically, this includes two Influenza A strains (H1N1 and H3N2) and one Influenza B strain.

What does the term 'quadrivalent' refer to in the context of influenza vaccines?

Quadrivalent refers to an influenza vaccine that contains antigens from four different influenza virus strains. In addition to the three strains found in trivalent vaccines (Influenza A H1N1, Influenza A H3N2, and one Influenza B lineage), it includes a second Influenza B lineage (typically B/Yamagata).

When did the WHO first issue recommendations for influenza vaccine formulations?

The World Health Organization (WHO) began issuing annual recommendations for influenza vaccine formulations in 1999.

What is the purpose of having separate recommendations for the Northern and Southern Hemispheres?

Separate recommendations are necessary because the influenza seasons in the Northern and Southern Hemispheres occur at different times of the year. Aligning vaccine strains with the circulating viruses in each hemisphere maximizes the potential effectiveness of the vaccine for the population in that region.

What was the recommended Influenza A H3N2 strain for the Northern Hemisphere in the 2017-2018 season?

For the 2017-2018 Northern Hemisphere influenza season, the recommended Influenza A H3N2 strain was similar to A/Hong Kong/4801/2014.

What Influenza B lineage was recommended for the Northern Hemisphere in the 2019-2020 season?

For the 2019-2020 Northern Hemisphere season, the WHO recommended an Influenza B strain similar to B/Colorado/06/2017 (B/Victoria lineage) and an Influenza B strain similar to B/Phuket/3073/2013 (B/Yamagata lineage).

What Influenza A H1N1 strain was recommended for the Southern Hemisphere in the 2021 season?

For the 2021 Southern Hemisphere influenza season, the recommended Influenza A H1N1 strains were similar to A/Victoria/2570/2019 for egg-based vaccines and similar to A/Wisconsin/588/2019 for cell- or recombinant-based vaccines.

What Influenza A H3N2 strain was recommended for the Southern Hemisphere in the 2022 season?

For the 2022 Southern Hemisphere influenza season, the recommended Influenza A H3N2 strain was similar to A/Darwin/9/2021 for egg-based vaccines and similar to A/Darwin/6/2021 for cell- or recombinant-based vaccines.

What Influenza B strains were recommended for the Southern Hemisphere in the 2023 season?

For the 2023 Southern Hemisphere influenza season, the recommended Influenza B strains were similar to B/Austria/1359417/2021 (B/Victoria lineage) and similar to B/Phuket/3073/2013 (B/Yamagata lineage) for both egg-based and cell- or recombinant-based vaccines.

Historical Annual Reformulations Of The Influenza Vaccine Wiki: The Evolving Landscape of Influenza Vaccine Composition

Dive in with Flashcard Learning!

When you are ready...
🎮 Play the Wiki2Web Clarity Challenge Game🎮

Introduction to Vaccine Reformulation

Global Recommendations

Since 1999, the World Health Organization (WHO) has provided critical annual recommendations for the composition of influenza vaccines. These recommendations are bifurcated, with distinct formulations advised for the Northern Hemisphere and the Southern Hemisphere, reflecting the differing seasonal patterns of influenza circulation in each region.

Strain Evolution

Historically, these recommendations primarily focused on trivalent vaccines (TIV), containing three specific influenza strains. However, since the 2012-2013 season, the WHO's guidance has also encompassed quadrivalent vaccines (QIV), which include an additional strain of Influenza B virus (specifically, the B/Yamagata lineage) to broaden protection.

Recent Shifts

A significant development occurred following the COVID-19 pandemic. The widespread implementation of non-pharmaceutical interventions led to a dramatic reduction in the isolation of the B/Yamagata influenza lineage, suggesting its potential eradication. Consequently, starting with the 2024 Southern Hemisphere season, regulatory bodies, including the WHO, have begun removing this lineage from vaccine recommendations.

Northern Hemisphere Vaccine Strains

The following table details the influenza virus strains recommended by the WHO for vaccine formulation in the Northern Hemisphere for each season, starting from 1998-1999. Note the transition to quadrivalent recommendations from the 2012-2013 season onwards.

Historical Data

NH Season	Influenza A (H1N1)	Influenza A (H3N2)	Influenza B (Victoria lineage)	Influenza B (Yamagata lineage)
1998–1999	A/Beijing/262/95-like	A/Sydney/5/97-like	N/A	B/Beijing/184/93-like
1999–2000	A/Beijing/262/95-like	A/Sydney/5/97-like	B/Shandong/7/97-like^{[note 1]}	B/Beijing/184/93-like^{[note 1]}
2000–2001	A/New Caledonia/20/99-like	A/Moscow/10/99-like	N/A	B/Beijing/184/93-like
2001–2002	A/New Caledonia/20/99-like	A/Moscow/10/99-like	N/A	B/Sichuan/379/99-like
2002–2003	A/New Caledonia/20/99-like	A/Moscow/10/99-like	B/Hong Kong/330/2001-like	N/A
2003–2004	A/New Caledonia/20/99-like	A/Moscow/10/99-like	B/Hong Kong/330/2001-like	N/A
2004–2005	A/New Caledonia/20/99-like	A/Fujian/411/2002-like	N/A	B/Shanghai/361/2002-like
2005–2006	A/New Caledonia/20/99-like	A/California/7/2004-like	N/A	B/Shanghai/361/2002-like
2006–2007	A/New Caledonia/20/99-like	A/Wisconsin/67/2005-like	B/Malaysia/2506/2004-like	N/A
2007–2008	A/Solomon Islands/3/2006-like	A/Wisconsin/67/2005-like	B/Malaysia/2506/2004-like	N/A
2008–2009	A/Brisbane/59/2007-like	A/Brisbane/10/2007-like	N/A	B/Florida/4/2006-like
2009–2010	A/Brisbane/59/2007-like	A/Brisbane/10/2007-like	N/A	B/Florida/4/2006-like
2010–2011	A/California/7/2009-like	A/Perth/16/2009-like	B/Brisbane/60/2008-like	N/A
2011–2012	A/California/7/2009-like	A/Perth/16/2009-like	B/Brisbane/60/2008-like	N/A
2012–2013	A/California/7/2009 (H1N1)pdm09-like^{[note 2]}	A/Victoria/361/2011-like	B/Brisbane/60/2008-like	B/Wisconsin/1/2010-like
2013–2014	A/California/7/2009 (H1N1)pdm09-like	A/Victoria/361/2011-like^{[note 3]}	B/Brisbane/60/2008-like	B/Massachusetts/2/2012-like
2014–2015	A/California/7/2009 (H1N1)pdm09-like	A/Texas/50/2012-like^{[note 4]}	B/Brisbane/60/2008-like	B/Massachusetts/2/2012-like
2015–2016	A/California/7/2009 (H1N1)pdm09-like	A/Switzerland/9715293/2013-like	B/Brisbane/60/2008-like	B/Phuket/3073/2013-like
2016–2017	A/California/7/2009 (H1N1)pdm09-like	A/Hong Kong/4801/2014-like	B/Brisbane/60/2008-like	B/Phuket/3073/2013-like
2017–2018	A/Michigan/45/2015 (H1N1)pdm09-like^{[note 5]}	A/Hong Kong/4801/2014-like	B/Brisbane/60/2008-like	B/Phuket/3073/2013-like
2018–2019	A/Michigan/45/2015 (H1N1)pdm09-like	A/Singapore/INFIMH-16-0019/2016-like	B/Colorado/06/2017-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2019–2020	A/Brisbane/02/2018-like	A/Kansas/14/2017-like	B/Colorado/06/2017-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2020–2021 (Egg-based)	A/Guangdong-Maonan/SWL1536/2019-like	A/Hong Kong/2671/2019-like	B/Washington/02/2019-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2020–2021 (Cell/Recombinant-based)	A/Hawaii/70/2019-like	A/Hong Kong/45/2019-like	B/Washington/02/2019-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2021–2022 (Egg-based)	A/Victoria/2570/2019-like	A/Cambodia/e0826360/2020-like	B/Washington/02/2019-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2021–2022 (Cell/Recombinant-based)	A/Wisconsin/588/2019-like	A/Cambodia/e0826360/2020-like	B/Washington/02/2019-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2022–2023 (Egg-based)	A/Victoria/2570/2019-like	A/Darwin/9/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2022–2023 (Cell/Recombinant-based)	A/Wisconsin/588/2019-like	A/Darwin/6/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2023–2024 (Egg-based)	A/Victoria/4897/2022-like	A/Darwin/9/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2023–2024 (Cell/Recombinant-based)	A/Wisconsin/67/2022-like	A/Darwin/6/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2024–2025 (Egg-based)	A/Victoria/4897/2022-like	A/Thailand/8/2022-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)^{[note 6]}
2024–2025 (Cell/Recombinant-based)	A/Wisconsin/67/2022-like	A/Massachusetts/18/2022-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)^{[note 6]}
2025–2026 (Egg-based)	A/Victoria/4897/2022-like	A/Croatia/10136RV/2023-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)^{[note 6]}
2025–2026 (Cell/Recombinant-based)	A/Wisconsin/67/2022-like	A/District of Columbia/27/2023-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)^{[note 6]}

Southern Hemisphere Vaccine Strains

This section outlines the influenza virus strains recommended by the WHO for vaccine formulation in the Southern Hemisphere, covering the period from 1999 to the present.

Historical Data

SH Season	Influenza A (H1N1)	Influenza A (H3N2)	Influenza B (Victoria lineage)	Influenza B (Yamagata lineage)
1999	A/Beijing/262/95-like	A/Sydney/5/97-like	N/A	B/Beijing/184/93-like
2000	A/New Caledonia/20/99-like	A/Moscow/10/99-like	B/Shandong/7/97-like^{[note 1]}	B/Beijing/184/93-like^{[note 1]}
2001	A/New Caledonia/20/99-like	A/Moscow/10/99-like	N/A	B/Sichuan/379/99-like
2002	A/New Caledonia/20/99-like	A/Moscow/10/99-like	N/A	B/Sichuan/379/99-like
2003	A/New Caledonia/20/99-like	A/Moscow/10/99-like	B/Hong Kong/330/2001-like	N/A
2004	A/New Caledonia/20/99-like	A/Fujian/411/2002-like	B/Hong Kong/330/2001-like	N/A
2005	A/New Caledonia/20/99-like	A/Wellington/1/2004-like	N/A	B/Shanghai/361/2002-like
2006	A/New Caledonia/20/99-like	A/California/7/2004-like	B/Malaysia/2506/2004-like	N/A
2007	A/New Caledonia/20/99-like	A/Wisconsin/67/2005-like	B/Malaysia/2506/2004-like	N/A
2008	A/Solomon Islands/3/2006-like	A/Brisbane/10/2007-like	N/A	B/Florida/4/2006-like
2009	A/Brisbane/59/2007-like	A/Brisbane/10/2007-like	N/A	B/Florida/4/2006-like
2010	A/California/7/2009-like	A/Perth/16/2009-like	B/Brisbane/60/2008-like	N/A
2011	A/California/7/2009-like	A/Perth/16/2009-like	B/Brisbane/60/2008-like	N/A
2012	A/California/7/2009 (H1N1)pdm09-like^{[note 2]}	A/Perth/16/2009-like	B/Brisbane/60/2008-like	N/A
2013	A/California/7/2009 (H1N1)pdm09-like	A/Victoria/361/2011-like	B/Brisbane/60/2008-like	B/Wisconsin/1/2010-like
2014	A/California/7/2009 (H1N1)pdm09-like	A/Texas/50/2012-like^{[note 4]}	B/Brisbane/60/2008-like	B/Massachusetts/2/2012-like
2015	A/California/7/2009 (H1N1)pdm09-like	A/Switzerland/9715293/2013-like	B/Brisbane/60/2008-like	B/Phuket/3073/2013-like
2016	A/California/7/2009 (H1N1)pdm09-like	A/Hong Kong/4801/2014-like	B/Brisbane/60/2008-like	B/Phuket/3073/2013-like
2017	A/Michigan/45/2015 (H1N1)pdm09-like^{[note 5]}	A/Hong Kong/4801/2014-like	B/Brisbane/60/2008-like	B/Phuket/3073/2013-like
2018	A/Michigan/45/2015 (H1N1)pdm09-like	A/Singapore/INFIMH-16-0019/2016-like	B/Brisbane/60/2008-like	B/Phuket/3073/2013-like
2019	A/Michigan/45/2015 (H1N1)pdm09-like	A/Switzerland/8060/2017-like	B/Colorado/06/2017-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2020	A/Brisbane/02/2018-like	A/South Australia/34/2019-like	B/Washington/02/2019-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2021 (Egg-based)	A/Victoria/2570/2019-like	A/Hong Kong/2671/2019-like	B/Washington/02/2019-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2021 (Cell/Recombinant-based)	A/Wisconsin/588/2019-like	A/Hong Kong/45/2019-like	B/Washington/02/2019-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2022 (Egg-based)	A/Victoria/2570/2019-like	A/Darwin/9/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2022 (Cell/Recombinant-based)	A/Wisconsin/588/2019-like	A/Darwin/6/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2023 (Egg-based)	A/Sydney/5/2021-like	A/Darwin/9/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2023 (Cell/Recombinant-based)	A/Sydney/5/2021-like	A/Darwin/6/2021-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)
2024 (Egg-based)	A/Victoria/4897/2022-like	A/Thailand/8/2022-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)^{[note 6]}
2024 (Cell/Recombinant-based)	A/Wisconsin/67/2022-like	A/Massachusetts/18/2022-like	B/Austria/1359417/2021-like (Victoria lineage)	B/Phuket/3073/2013-like (Yamagata lineage)^{[note 6]}

Notes and Clarifications

Explanations

The term "-like virus" indicates strains that are antigenically similar to the reference viruses used in vaccine composition recommendations.

Note 1: For the 1999-2000 season, the recommendation allowed for either the B/Shandong/7/97-like or B/Beijing/184/93-like strain for Influenza B.
Note 2: (H1N1)pdm09 refers to the nomenclature for the 2009 pandemic H1N1 virus, indicating a specific strain rather than a new classification.
Note 3: The recommendation for A/Texas/50/2012 as the A(H3N2) component was made due to antigenic drift observed in earlier A/Victoria/361/2011-like vaccine viruses, particularly after adaptation to egg-based propagation.
Note 4: A/Texas/50/2012 is an A(H3N2) virus whose antigenic properties, after adaptation to egg growth, remained similar to recently circulating cell-propagated A(H3N2) viruses, including A/Victoria/361/2011.
Note 5: A/Michigan/45/2015 was recommended to replace A/California/7/2009 to potentially improve protection against emerging subclades.
Note 6: The WHO, FDA, and EMA advise excluding the B/Yamagata lineage antigen from influenza vaccines, as it is no longer considered warranted due to lack of circulation.

Teacher's Corner

Edit and Print this course in the Wiki2Web Teacher Studio

Edit and Print Materials from this study in the wiki2web studio

Click here to open the "Historical Annual Reformulations Of The Influenza Vaccine" Wiki2Web Studio curriculum kit

Use the free Wiki2web Studio to generate printable flashcards, worksheets, exams, and export your materials as a web page or an interactive game.

True or False?

Test Your Knowledge!

Gamer's Corner

Are you ready for the Wiki2Web Clarity Challenge?

Learn about historical_annual_reformulations_of_the_influenza_vaccine while playing the wiki2web Clarity Challenge game.

Unlock the mystery image and prove your knowledge by earning trophies. This simple game is addictively fun and is a great way to learn!

Play now

Explore More Topics

Discover other topics to study!

juridical person

radio new zealand

james boswell

francisco del rosario'sánchez

References

It is recommended that A/Texas/50/2012 is used as the A(H3N2) vaccine component because of antigenic changes in earlier A/Victoria/361/2011-like vaccine viruses (such as IVR-165) resulting from adaptation to propagation in eggs.

A/Texas/50/2012 is an A(H3N2) virus that following adaptation to growth in eggs has maintained antigenic properties similar to the majority of recently circulating cell-propagated A(H3N2) viruses including A/Victoria/361/2011.

The WHO, the FDA, and the EMA advise that the B/Yamagata lineage antigen should be excluded from influenza vaccines as it is no longer warranted.

A full list of references for this article are available at the Historical annual reformulations of the influenza vaccine Wikipedia page

Feedback & Support

To report an issue with this page, or to find out ways to support the mission, please click here.

Disclaimer

Important Notice

This content has been generated by an AI and is intended for informational and educational purposes only. It is based on data publicly available from Wikipedia and may not reflect the most current information or nuances. The data presented is a snapshot in time and may not be entirely accurate, complete, or up-to-date.

This is not medical advice. The information provided herein should not be considered a substitute for professional medical consultation, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider or public health official regarding any questions you may have about influenza, vaccines, or any medical condition. Never disregard professional medical advice or delay seeking it due to information obtained from this resource.

The creators of this page are not liable for any errors or omissions, nor for any actions taken based on the information presented.

The Evolving Landscape of Influenza Vaccine Composition

Dive in with Flashcard Learning!

Introduction to Vaccine Reformulation

Global Recommendations

Strain Evolution

Recent Shifts

Northern Hemisphere Vaccine Strains

Historical Data

Southern Hemisphere Vaccine Strains

Historical Data

Related Topics

Influenza Virology

Epidemiology

Vaccine Development

Notes and Clarifications

Explanations

Teacher's Corner

Edit and Print this course in the Wiki2Web Teacher Studio

True or False?

Test Your Knowledge!

Gamer's Corner

Are you ready for the Wiki2Web Clarity Challenge?

Explore More Topics

Discover other topics to study!

References

References

Feedback & Support

To report an issue with this page, or to find out ways to support the mission, please click here.

Disclaimer

Important Notice

The Evolving Landscape of Influenza Vaccine Composition

💡 Dive in with Flashcard Learning! 💡

Introduction to Vaccine Reformulation 📅

🌍 Global Recommendations

🧬 Strain Evolution

🦠 Recent Shifts

Northern Hemisphere Vaccine Strains ❄️

📊 Historical Data

Southern Hemisphere Vaccine Strains ☀️

📊 Historical Data

Related Topics 🔗

🔬 Influenza Virology

📈 Epidemiology

💉 Vaccine Development

Notes and Clarifications ℹ️

📝 Explanations

Teacher's Corner 🧑‍🏫

Edit and Print this course in the Wiki2Web Teacher Studio

True or False? 🤔

❓ Test Your Knowledge! ❓

Gamer's Corner 🎮

Are you ready for the Wiki2Web Clarity Challenge?

Explore More Topics

📜 Discover other topics to study!

References

📜 References

Feedback & Support 👍

To report an issue with this page, or to find out ways to support the mission, please click here.

Disclaimer ⚠️

📜 Important Notice

Dive in with Flashcard Learning!

Introduction to Vaccine Reformulation

Global Recommendations

Strain Evolution

Recent Shifts

Northern Hemisphere Vaccine Strains

Historical Data

Southern Hemisphere Vaccine Strains

Historical Data

Related Topics

Influenza Virology

Epidemiology

Vaccine Development

Notes and Clarifications

Explanations

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice