A H5N1 vaccine is an

influenza vaccine Influenza vaccines, colloquially known as flu shots or the flu jab, are vaccines that protect against infection by influenza viruses. New versions of the vaccines are developed twice a year, as the influenza virus rapidly changes. While their ...

intended to provide immunization to influenza A virus subtype H5N1. Vaccination of poultry against the avian H5N1 influenza

epizootic In epizoology, an epizootic (or epizoötic, from Greek: ''epi-'' "upon" + ''zoon'' "animal") is a disease event in a nonhuman animal population analogous to an epidemic in humans. An epizootic disease (or ) may occur in a specific locale (an ...

is widespread in certain countries. Some vaccines also exist for use in humans. As of July 2024, these include Aflunov, Audenz, Celldemic, and Incellipan. The

hemagglutinin The term hemagglutinin (alternatively spelt ''haemagglutinin'', from the Greek , 'blood' + Latin , 'glue') refers to any protein that can cause red blood cells (erythrocytes) to clump together (" agglutinate") ''in vitro''. They do this by bindin ...

protein is the main viral antigen of influenza A viruses, including the H5N1 subtype. Vaccination can induce antibodies that block the functions of the H5 hemagglutinin and neutralize virus infectivity. The influenza virus is highly variable - the H5N1 virus infecting cattle in the USA is different from the viruses that showed up in poultry in 1997. However licensed vaccines can be updated in a process similar to that used for updating seasonal influenza vaccines.

Timeline

February 2025, the

Public Health Agency of Canada The Public Health Agency of Canada (PHAC; ) is an agency of the Government of Canada that is responsible for public health, emergency preparedness and response, and infectious and chronic disease control and prevention. History The PHAC was f ...

announced it had secured 500,000 initial doses of GSK's Arepanrix H5N1 human vaccine to protect people most at risk. This includes farmers, healthcare providers, and veterinarians. This vaccine incorporates antigenic material from the A/American wigeon/South Carolina/22-000345-001/2021 (H5N1)-like strain. In December 2024 the UK government announced the purchase of five million doses of human H5 influenza vaccine to boost the country’s resilience in the event of a possible H5 influenza pandemic. The vaccine will be manufactured by CSL Seqirus UK Limited. The vaccine is based on the A/H5N8/Astrakhan/3212/2020 clade 2.3.4.4b strain of influenza. If needed, the H5 vaccine could be used while a pandemic-specific vaccine is developed and produced. In July 2024, CSL Seqirus, Sanofi and GSK have collectively secured $72 million in funding from the U.S. health department to boost the country’s supply of bird flu vaccines. In June 2024, the

European Commission The European Commission (EC) is the primary Executive (government), executive arm of the European Union (EU). It operates as a cabinet government, with a number of European Commissioner, members of the Commission (directorial system, informall ...

's Health Emergency Preparedness and Response Authority (HERA) signed a four-year contract with CSL Seqirus to secure 665,000 pre-pandemic vaccines with a provision for a further 40 million doses of avian flu vaccines. The member states participating in the contract are 15 of the 36 countries that have signed the EU's Joint Procurement Agreement for Medical Countermeasures, which includes all EU and EEA Member States. These fifteen countries are:

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

Cyprus Cyprus (), officially the Republic of Cyprus, is an island country in the eastern Mediterranean Sea. Situated in West Asia, its cultural identity and geopolitical orientation are overwhelmingly Southeast European. Cyprus is the List of isl ...

Lithuania Lithuania, officially the Republic of Lithuania, is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea, bordered by Latvia to the north, Belarus to the east and south, P ...

Malta Malta, officially the Republic of Malta, is an island country in Southern Europe located in the Mediterranean Sea, between Sicily and North Africa. It consists of an archipelago south of Italy, east of Tunisia, and north of Libya. The two ...

, the

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

Slovenia Slovenia, officially the Republic of Slovenia, is a country in Central Europe. It borders Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the south and southeast, and a short (46.6 km) coastline within the Adriati ...

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

, and

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. In May 2024, CSL Seqirus was selected by the US government to supply 4.8 million doses of an H5 vaccine to the National Pre-Pandemic Influenza Vaccine Stockpile program. The vaccine is well matched to the H5N1 strains currently circulating in wild birds and cattle. In January 2020, the US approved Audenz, an adjuvanted influenza A (H5N1) monovalent vaccine. Audenz is indicated for active immunization for the prevention of influenza A/turkey/Turkey/1/2005 NIBRG-23. In the event of an outbreak of the disease in humans, the strain could be updated in a process similar to that used for updating seasonal vaccines. In November 2013, the US approved an experimental H5N1 bird flu vaccine to be held in stockpiles. In a trial including 3,400 adults, 91% of people age 18–64 and 74% of people age 65 or older formed an immune response sufficient to provide protection. Reported adverse effects were generally mild, with pain at the injection site being the most common adverse effect.

List of licensed and candidate vaccines

A "candidate" vaccine is one which has been developed to be safe and effective, but has not received marketing authorization. As of January 2025, the following vaccines are available or under development: * Adjupanrix: approved for medical use in the European Union in October 2009. Adjupanrix contains the flu strain A/VietNam/1194/2004 NIBRG 14 (H5N1). * Aflunov: A vaccine for people aged six months of age and older, approved for medical use in the European Union in November 2010. Aflunov contains the flu strain A/turkey/Turkey/1/2005 (H5N1)-like strain (NIBRG-23) (clade 2.2.1). * Audenz: A vaccine for adults that contains the killed A/Astrakhan/3212/2020 (H5N8)-like strain. * Foclivia: approved for medical use in the European Union in October 2009. A vaccine that contains the A/Vietnam/1194/2004 (H5N1) flu strain. * Pumarix: A vaccine approved for medical use in the European Union in March 2011. In February 2025, the Committee for Veterinary Medicinal Products of the

European Medicines Agency The European Medicines Agency (EMA) is an agency of the European Union (EU) in charge of the evaluation and supervision of pharmaceutical products. Prior to 2004, it was known as the European Agency for the Evaluation of Medicinal Products ...

adopted a positive opinion, recommending the granting of a marketing authorization for the veterinary medicinal product Vectormune HVT-AIV, concentrate and solvent for suspension for injection, intended for one day-old chickens. The applicant for this veterinary medicinal product is CEVA Sante Animale. Vectormune HVT-AIV is a cell-associated, live recombinant vector vaccine containing one active substance: the recombinant live turkey herpes virus (HVT, Marek’s disease serotype 3) genetically modified to express the hemagglutinin 5 (H5) encoding the gene of highly pathogenic avian influenza virus (HPAIV) H5N1. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged. Some older H5N1 vaccines for humans that have been licensed are: *

Sanofi Pasteur Sanofi Pasteur is the vaccines division of the French multinational pharmaceutical company Sanofi. Sanofi Pasteur is the largest company in the world devoted entirely to vaccines. It is one of four global producers of the yellow fever vaccin ...

's vaccine approved by the United States in April 2007. *

GlaxoSmithKline GSK plc (an acronym from its former name GlaxoSmithKline plc) is a British Multinational corporation, multinational Pharmaceutics, pharmaceutical and biotechnology company with headquarters in London. It was established in 2000 by a Mergers an ...

's vaccine Prepandrix approved by the European Union in May 2008. * CSL Limited's vaccine Panvax approved by Australia in June 2008.

Vaccine production

H5N1 continually mutates, meaning vaccines based on current samples of avian H5N1 cannot be depended upon to work in the case of a future pandemic of H5N1. While there can be some cross-protection against related flu strains, the best protection would be from a vaccine specifically produced for any future pandemic flu virus strain. Daniel R. Lucey, co-director of the Biohazardous Threats and Emerging Diseases graduate program at Georgetown University, has made this point, "There is no

H5N1 Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus, which causes the disease avian influenza (often referred to as "bird flu"). It is enzootic (maintained in the population) in many bird populations, and also panzoo ...

pandemic A pandemic ( ) is an epidemic of an infectious disease that has a sudden increase in cases and spreads across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. Widespread endemic (epi ...

so there can be no pandemic

vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifi ...

." However, "pre-pandemic vaccines" have been created; are being refined and tested; and do have some promise both in furthering research and preparedness for the next pandemic. Vaccine manufacturing companies are being funded to increase flexible capacity so that if a pandemic vaccine is needed, facilities will be available for rapid production of large amounts of a vaccine specific to a new pandemic strain.

Notes

References

External links