FDA approves first adjuvanted vaccine for prevention of H5N1 avian influenza for National Stockpile

FDA approved the first adjuvanted vaccine for the prevention of H5N1 influenza, commonly known as avian or bird flu. The vaccine, Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted, is for use in people aged 18 years and older who are at increased risk of exposure to the H5N1 influenza virus.  

The H5N1 avian influenza vaccine is not intended for commercial availability. The US Department of Health and Human Services has purchased the vaccine from the manufacturer, ID Biomedical Corp. of Quebec, Quebec City, Canada (a subsidiary of GlaxoSmithKline Biologicals), for inclusion within the National Stockpile for distribution by public health officials if needed. 

“The FDA approval of first adjuvanted vaccine for prevention of H5N1 avian influenza can be viewed as another landmark approval that is designed to safeguard the health of the public, particularly as relates to this strain of the influenza virus, which was and still remains a major health concern,” said Formulary advisor Abimbola Farinde, PharmD, MS, who serves on the faculty at Columbia Southern University, Orange Beach, Ala. “This approval demonstrates FDA's initiative to take steps to be prepared in the event of an epidemic.”

Avian influenza is an infectious disease of birds caused by certain influenza A viruses. Most avian influenza A viruses do not infect people. However some viruses, such as H5N1, have caused serious illness and death in people outside of the United States, mostly among people who have been in close contact with infected and ill poultry. When people do become infected with H5N1, about 60%  die, according to the World Health Organization. H5N1 is an influenza virus with pandemic potential because it continues to infect wild birds with occasional outbreaks of influenza disease in poultry populations, and most humans have no immunity to it.

The vaccine is made using an egg-based manufacturing process, which is also used for ID Biomedical Corp.’s seasonal influenza vaccine, FluLaval. It contains the adjuvant AS03, an oil-in-water emulsion. An adjuvant is a substance incorporated into some vaccines to enhance or direct the immune response of the vaccinated individual. 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. 

The H5N1 component and the AS03 adjuvant component are supplied in two separate vials, which must be combined prior to use. The vaccine is administered via intramuscular injection in two doses, 21 days apart.

The evaluation of safety compared approximately 3,400 adults aged 18 years and older who received the vaccine to about 1,100 adults who received placebo in a multicenter study. Injection-site pain was the most common side effect among the vaccine recipients reported during the clinical studies. Muscle aches, headache, fatigue, and injection-site redness, and swelling were also common. To determine how well the vaccine works, the immune response was evaluated in about 2,000 of the vaccinated adults. Results showed that 91% of individuals between the aged 18 and 64 years and 74% of individuals aged 65 years and older who received the 2-dose regimen developed antibodies at a level that is expected to reduce the risk of getting influenza.

The manufacturer will collaborate with FDA and other US governmental agencies on plans to collect additional safety and effectiveness data through US government-sponsored studies of the vaccine, in the event that it is used during an H5N1 influenza virus pandemic.