On November 22, 2013, FDA licensed (approved) the second vaccine for use in the United States for the prevention of H5N1 influenza, commonly referred to as avian influenza or “bird flu.” The vaccine, Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted, is the first adjuvanted influenza vaccine approved by FDA and is for use in people 18 years of age and older who are at increased risk of exposure to the H5N1 influenza virus subtype contained in the vaccine.
The vaccine is administered as a two-dose regimen, 21 days apart, via intramuscular injection. It is manufactured by ID Biomedical Corporation of Quebec (IDB), a subsidiary of GlaxoSmithKline Biologicals (GSK). The egg-based manufacturing process is also used for IDB’s seasonal influenza vaccine, FluLaval, which was approved by FDA in 2006.
The vaccine will not be commercially available. It has been purchased by the federal government for inclusion within the U.S. government’s National Stockpile for distribution by public health officials if needed. It could be used in the event that the H5N1 avian influenza virus develops the capability to spread efficiently from person-to-person resulting in the rapid spread of disease across the globe. Vaccines are critical to help counter the spread of influenza disease during a pandemic.
What is the difference between seasonal and H5N1 avian influenza?
Both seasonal and avian influenza are respiratory illnesses that have many of the same initial symptoms such as high fever and achy muscles. Seasonal influenza is typically caused by certain Type A influenza viruses (subtype H1N1 and H3N2 viruses) and by Type B viruses. It occurs yearly, mainly in the late fall and winter, and is spread easily from person-to-person. Seasonal influenza can be a serious disease, particularly in children, pregnant women and the elderly, and can lead to hospitalization and sometimes even death.
H5N1 avian influenza is caused only by Type A influenza viruses belonging to the H5N1 subtype. H5N1 viruses commonly circulate in birds, but can be passed from birds to humans. This can occur at any time of the year. H5N1 viruses rarely infect people, but when they do, they can cause very serious illness, with about 60 percent of cases dying from the disease. In the majority of cases, the person became infected with H5N1 influenza virus after direct or close contact with infected poultry.
In the U.S., there have been no cases of H5N1 influenza in people.
H5N1 viruses continue to circulate widely in wild birds with occasional outbreaks in poultry populations, and most people have no immunity to it. Public health experts are concerned that H5N1 viruses could change over time and become capable of spreading easily among people.
What does it mean that the vaccine is adjuvanted?
An adjuvant is a substance added to this vaccine to enhance the immune response of vaccinated individuals. The adjuvant makes it possible to use a small amount of influenza protein per dose of vaccine to elicit the desired immune response in an individual to prevent influenza disease. Reducing the amount of influenza protein per dose helps to increase the total number of doses of a safe and effective vaccine available for the public during a pandemic.
Which adjuvant is used in the vaccine?
The vaccine contains the adjuvant AS03, an oil-in-water emulsion. The AS03 adjuvant is made up of the oily compounds, D,L-alpha-tocopherol (vitamin E) and squalene, and an emulsifier known as polysorbate 80, and water containing small amounts of salts.
The H5N1 component and the AS03 adjuvant component are supplied in two separate vials, which must be combined prior to use.
Are there other adjuvanted vaccines approved by FDA for use in the United States?
Yes. Although this is the first influenza vaccine that contains an adjuvant, this is not the first FDA-approved vaccine to include an adjuvant. Aluminum containing adjuvants have been safely used in vaccines for over six decades and have only uncommonly been associated with severe local reactions. In addition, Cervarix, an FDA-approved vaccine for the prevention of cervical cancer, is formulated with the adjuvant AS04, a combination of aluminum hydroxide and monophosphoryl lipid A. (MPL) MPL is a detoxified form of a substance purified from the cell walls of certain bacteria.
While this is the first vaccine approved by FDA that has the AS03 adjuvant in its formulation, this adjuvant has been widely used in influenza vaccines that were administered in other countries during the 2009 influenza pandemic.
What is D,L-alpha-tocopherol?
D,L-alpha-tocopherol is the scientific, chemical name for vitamin E.
Squalene is a substance naturally found in the human body, as well as in animals and plants. Squalene is manufactured in our livers and circulates in our bloodstream reaching various tissues, muscles and organs, with the highest amount found in our skin. Squalene is an essential building block to make certain hormones and other substances in our bodies.
Squalene is also found in a variety of foods such as eggs and vegetable oils. In addition, cosmetics, over-the-counter medicines and dietary health supplements contain squalene derived from the liver of sharks, which is a large source of squalene.
The squalene in this vaccine is also derived from the liver of sharks and is highly purified for the vaccine manufacturing process.
What is polysorbate 80?
Polysorbate 80 is a substance that is used primarily as an emulsifier in food products, cosmetics, vitamins, medicines, and vaccines. Emulsifiers help ingredients mix together and keep them from separating, most commonly oil and water. In medicines, such as vaccines, it also functions as a stabilizer of the formulation. The substance is a derivative of sorbitol, a type of sugar, and oleic acid, a naturally occurring fatty acid.
Is the vaccine effective?
Yes, The immune response was evaluated in about 2,000 adults 18 years of age and older in a multi-center study. The results showed that 91 percent of individuals between the ages of 18 and 64 years and 74 percent of individuals 65 years and older who received the two-dose regimen developed antibodies at a level that is expected to reduce the risk of becoming ill due to H5N1 influenza.
Is the vaccine safe?
Yes. The evaluation of safety compared approximately 3,400 adults 18 years of age and older who received the vaccine to about 1,100 who received placebo. The most common side effect reported from the clinical study participants was injection site pain. Muscle aches, headache, fatigue and injection site redness and swelling were also common.
Is this the vaccine that is linked with an increased risk of narcolepsy in some other countries?
No, that was a different influenza vaccine. Pandemrix, which contains the AS03 adjuvant and H1N1 influenza virus subtype, is not approved by FDA for use in the U.S. It is also manufactured by GSK, but has a different manufacturing process from that used to manufacture Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted.
Pandemrix was used outside of the U.S., primarily in Europe, during the 2009 (H1N1) influenza pandemic in which approximately 31 million people received the vaccine.
Narcolepsy is a rare, chronic disorder of the central nervous system where the brain is unable to control sleep-wake cycles. At various times throughout the day, people with narcolepsy experience irresistible and sudden bouts of sleep, which can last from a few seconds to several minutes.
An increased risk of narcolepsy following Pandemrix was reported in some European countries among children, adolescents, and adults. Because these reported findings may not be generalizable to Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted or to the U.S. population, the relevance of the reported increased risk of narcolepsy following vaccination with Pandemrix to this vaccine is unknown.
Did FDA take into consideration the risk of narcolepsy following vaccination with Pandemrix in its decision to approve Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted?
Yes. FDA’s decision to approve the vaccine for use in the U.S. took into account the available immunogenicity and safety data for Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted. Of note, no cases of narcolepsy were reported in the clinical studies of this vaccine. In addition, FDA also evaluated post-marketing safety data for Pandemrix and the available epidemiological data for disease caused by H5N1 influenza viruses. These viruses, which have pandemic potential, can cause severe illness with a resulting high death rate in those who become infected.
Furthermore, FDA convened its Vaccines and Related Biological Products Advisory Committee in November 2012 to discuss and obtain additional scientific input on the safety and effectiveness of Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted. The Committee discussed, among other topics, the finding of narcolepsy in other countries associated with Pandemrix and considered the studies that were available at the time. The 14-member Committee voted unanimously that the immunogenicity and safety data support the licensure of Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted.
FDA has determined the benefits of the vaccine outweigh potential risks because of the high death rate in people infected with H5N1 influenza virus, and the lack of available effective medical countermeasures for prevention or treatment of disease once a person is infected,
As FDA does for all vaccines, the safety of Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted will be closely monitored with use in the U.S
Will the vaccine be made available to the public?
Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted is not intended for commercial availability. The U.S. Department of Health and Human Services has purchased the vaccine from the manufacturer, ID Biomedical Corporation of Quebec, Quebec City, Canada (a subsidiary of GlaxoSmithKline Biologicals), for inclusion within the U.S. National Stockpile for distribution by public health officials if needed.