WHO recommendations for influenza virus vaccine composition for the 2018-2019 Northern hemisphere season
On 19-21 February 2018 the World Health Organization (WHO) agreed on the recommended composition of the trivalent influenza vaccine for the northern hemisphere 2018-2019 influenza season; 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). The WHO recommendations are made with a knowledge of the currently circulating viruses globally. WHO recommended two changes, compared to the current trivalent and quadrivalent vaccines for the 2017–2018 season in the northern hemisphere influenza season.
On 19-21 February 2018 in Geneva, the World Health Organization (WHO) has agreed on the recommended composition of the trivalent influenza vaccine for the northern hemisphere 2018-2019 influenza season as:
- an A/Michigan/45/2015 (H1N1)pdm09-like virus;
- an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus;
- a B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage).
For quadrivalent vaccines containing two influenza B viruses, also a B/Phuket/3073/2013-like virus is recommended.
The WHO recommendations are made with a knowledge of the currently circulating viruses globally. WHO recommended two changes, compared to the current trivalent and quadrivalent vaccines for the 2017–2018 season in the northern hemisphere influenza season. Similar to the 2018 southern hemisphere vaccine, the A(H3N2) component was changed to an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus. In trivalent vaccines the B component was switched to a B/Victoria -lineage B/Colorado/06/2017-like virus, representing the emergent strain of B/Victoria with the amino acid deletions Δ162-163 in haemagglutinin (HA). The A(H1N1)pdm09 component in trivalent and quadrivalent vaccines and the B/Yamagata component in quadrivalent vaccines remained the same.
Almost all of the currently circulating A(H1N1)pdm09 viruses were antigenically indistinguishable from the current vaccine virus A/Michigan/45/2015, and the same component remained the same.
Almost all of the currently circulating A(H3N2) viruses belonged to the HA phylogenetic clade 3C.2a. WHO recommended the inclusion of a A/Singapore/INFIMH-160019/2016-like virus that belongs to the 3C.2a1 subclade. Recent A(H3N2) viruses were better inhibited by antisera raised against this egg-propagated virus, compared to antisera raised against the egg-propagated A/Hong Kong/4801/2014, which is the current 2017-2018 A(H3N2) vaccine component.
Globally, both B virus lineages continue to co-circulate with B/Yamagata lineage largely predominating. The B/Yamagata component was only included in the 2017-2018 quadrivalent vaccine, while all of the circulating B/Yamagata/16/88 lineage viruses were well inhibited by antisera raised against B/Phuket/3073/2013. The same component was retained for the quadrivalent 2018-2019 vaccine.
WHO recommended now the inclusion of the B/Victoria lineage into the trivalent vaccine for the northern hemisphere 2018-2019 influenza season. The recommended vaccine virus B/Colorado/06/2017 belongs to clade 1A and carries the characteristic two amino acid deletions K162 and N163 in HA. Though the level of detection of B/Victoria viruses remain low, a substantial and increasing proportion carries this deletion.
Further antigenic and genetic characteristics of recent seasonal influenza viruses are described in the full report of the recommendation.
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Seasonal influenza vaccination strategies
The immunity that is elicited by influenza vaccines is not as long lived as the immunity following natural influenza infection. This is especially so for individuals in the so-called risk groups, hence people have to be vaccinated annually. There are three influenza immunisation strategies used in Europe: to protect the vulnerable, to protect healthy children, adolescents and adults and to reduce overall influenza transmission.
Types of seasonal influenza vaccine
Injected trivalent inactivated influenza vaccines are most commonly used throughout the world. Influenza antigen preparation varies between manufacturers. The inactivated influenza vaccines available in the EU/EEA may contain either split virion influenza virus products or subunit influenza products. Adjuvanted inactivated subunit influenza vaccine for older people is available in some EU/EEA Member States and is since 2015 authorised for younger children in Canada but not yet in Europe.
Yearly updates of influenza vaccines
An update of seasonal influenza vaccines is needed yearly, since influenza viruses constantly evolve. How effective the seasonal influenza vaccine is each season depends on the match between the selected vaccine viruses and those found circulating, and will therefore vary from year to year.
Influenza Virus Characterisation Reports, summary Europe
The influenza virus characterisation reports give an overview of circulating influenza viruses in Europe. They provide details on the current vaccine strains, summarise the development of the viruses since the last report, and closely follow the main developments for the ongoing influenza season.
See previous recommendations
WHO recommendations for influenza virus vaccine composition for the 2017-18 northern hemisphere season
WHO recommendations for influenza virus vaccine composition for the 2018 southern hemisphere influenza season
WHO issues recommendation on the composition of influenza virus vaccines for the northern hemisphere 2016-2017
WHO recommendations for influenza virus vaccine composition for the 2017 southern hemisphere season
WHO issues recommendation on the composition of influenza virus vaccines for the northern hemisphere 2015-2016
WHO recommendations for influenza virus vaccine composition for the 2016 southern hemisphere season
WHO issues recommendation on composition of influenza virus vaccines for northern hemisphere 2014-2015
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Prevention and control of seasonal influenza
Seasonal influenza is a vaccine-preventable disease that each year infects approximately 10 to 30 % of Europe's population, and causes hundreds of thousands of hospitalisations across Europe. Vaccination is the most effective form of influenza prevention. Apart from vaccination and antiviral treatment the public health management includes personal protective measures.
Flu News Europe: Weekly influenza updates
In collaboration with WHO Regional Office for Europe, ECDC monitors and reports on influenza activity in Europe on a weekly basis throughout the flu season. The latest data is published in the report Flu News Europe.
Influenza season summaries
In the Influenza season summaries you find the ECDC main outputs during the influenza season as well as an Infographic showing a summary of the season.