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Influenza A Virus Vaccine (H5N1)

Medically reviewed by Last updated on Jul 3, 2020.


(in floo EN za aye VYE rus vak SEEN H5N1)

Index Terms

  • Audenz
  • Avian Influenza Virus Vaccine
  • Bird Flu Vaccine
  • H5N1 Influenza Vaccine
  • Highly Pathogenic Avian Influenza (HPAI) A (H5N1) Virus Vaccine
  • Influenza Virus Vaccine (H5N1)
  • Influenza Virus Vaccine (Monovalent)
  • Q-Pan H5N1 Influenza Vaccine

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Injection, emulsion [monovalent]: GlaxoSmithKline product: Adjuvanted Hemagglutinin [A/Indonesia/05/2005 (H5N1)] 3.75 mcg/0.5 mL (5 mL) [contains egg protein, polysorbate 80, and thimerosal]

Injection, suspension [monovalent]: Sanofi Pasteur product: Hemagglutinin [A/Vietnam/1203/2004 (H5N1)] 90 mcg/mL (5 mL) [contains chicken and egg protein, porcine gelatin, and thimerosal]

Pharmacologic Category

  • Vaccine
  • Vaccine, Inactivated (Viral)


Promotes active immunity to influenza A H5N1 (avian).

Onset of Action

Audenz: 4-fold increase in antibody titers (measured by hemagglutination inhibition [HI]) occurred in up to 96% of patients 6 months to 17 years of age, 95% of patients 18 to 64 years of age, and 86% of patients ≥65 years of age 21 days after the second dose.

GlaxoSmithKline product (adjuvanted): 4-fold increase in antibody titers (measured by HI) occurred in up to 90% of patients 18 to 64 years of age and 74% of patients ≥65 years of age 21 days after the second dose.

Sanofi Pasteur product: 4-fold increase in antibody titers (measured by HI) occurred in up to 58% of patients 28 days after the second dose (Treanor 2006).

Use: Labeled Indications

Influenza A (H5N1) prevention:

Seqirus (Audenz) and GlaxoSmithKline products (adjuvanted): Active immunization of persons ≥6 months of age at increased risk of exposure to the influenza A (H5N1) virus subtype contained in the vaccine.

Note: Audenz: Use in persons 6 months through 17 years of age received accelerated approval based on the immune response elicited by Audenz. Effectiveness of the seasonal vaccine made by the same process has not been confirmed for this age group. Continued approval for use in this age group may be contingent upon verification and description of clinical benefit in confirmatory trials.

Sanofi Pasteur product: Active immunization of persons 18 to 64 years of age at increased risk of exposure to the influenza A (H5N1) virus subtype contained in the vaccine.


Seqirus product (Audenz) (MF59-adjuvanted): Severe allergic reactions (eg, anaphylaxis) to any component of the vaccine or after a previous dose of an influenza vaccine.

GlaxoSmithKline product (AS03-adjuvanted): Severe allergic reactions (eg, anaphylaxis) to any component of the vaccine, including egg protein, or after a previous dose of an influenza vaccine.

Sanofi Pasteur product: There are no contraindications listed in the manufacturer's labeling.

Dosing: Adult

Influenza A (H5N1) prevention:

Seqirus (MF59-adjuvanted [Audenz]) and GlaxoSmithKline (AS03-adjuvanted) products: IM: 0.5 mL followed by a second 0.5 mL dose administered 21 days later.

Sanofi Pasteur product: Adults 18 to 64 years of age: IM: 1 mL followed by second 1 mL dose administered ~28 days later (acceptable range: 21 to 35 days).

Dosing: Pediatric

Influenza A subtype H5N1, immunization:

Note: Available vaccines are manufactured differently; dose volumes are different (eg, 0.25 mL vs 0.5 mL per dose); use precaution when verifying product selection and dose volume.

GlaxoSmithKline product (AS03-adjuvanted):

Infants ≥6 months, Children, and Adolescents ≤17 years: IM: 0.25 mL, followed by a second 0.25 mL dose 21 days later.

Adolescents ≥18 years: IM: 0.5 mL, followed by a second 0.5 mL dose 21 days later.

Seqirus product (MF59-adjuvanted [Audenz]):

Infants ≥6 months, Children, and Adolescents: IM: 0.5 mL, followed by a second 0.5 mL dose 21 days later.


GlaxoSmithKline product (AS03-adjuvanted): Prior to mixing, bring one vial of H5N1 antigen and one vial of AS03 adjuvant to room temperature (minimum of 15 minutes). Invert each vial to mix; do not use if particulate matter or discoloration are present. Withdraw contents of adjuvant vial and add to the H5N1 antigen vial. Mix thoroughly by inversion and label with the time and date of mixing on vial. Use within 24 hours of mixing.


For IM administration only. Gently shake prior to use. Inspect for particulate matter and discoloration prior to administration. Administer into the deltoid muscle; do not inject into the gluteal region or areas where there may be a major nerve trunk. Do not mix with other vaccines or injections; separate needles and syringes should be used for each injection (ACIP [Ezeanolue 2020]). To prevent syncope-related injuries, patients should be vaccinated while seated or lying down (ACIP [Ezeanolue 2020]). US law requires that the date of administration, the vaccine manufacturer, lot number of vaccine, and the administering person's name, title, and address be entered into the patient's permanent medical record.

GlaxoSmithKline product (AS03-adjuvanted): If vaccine is stored under refrigeration after mixing, bring to room temperature prior to administration (minimum 15 minutes). Mix thoroughly by inversion prior to administration.

Seqirus product (MF59-adjuvanted [Audenz]): Gently shake prior to administration; appearance should be milky white.

For patients at risk of hemorrhage following IM injection, the vaccine should be administered IM if, in the opinion of the physician familiar with the patient's bleeding risk, the vaccine can be administered by this route with reasonable safety. If the patient receives antihemophilia or other similar therapy, IM vaccination can be scheduled shortly after such therapy is administered. A fine needle (23 gauge or smaller) can be used for the vaccination and firm pressure applied to the site (without rubbing) for at least 2 minutes. The patient should be instructed concerning the risk of hematoma from the injection. Patients on anticoagulant therapy should be considered to have the same bleeding risks and treated as those with clotting factor disorders (ACIP [Ezeanolue 2020]).


Audenz and Sanofi Pasteur products: Store in a refrigerator at 2°C to 8°C (36°F to 46°F). Do not freeze. Discard if frozen. Protect from light.

GlaxoSmithKline product (adjuvanted): Prior to mixing, the H5N1 antigen and AS03 adjuvant vials should be stored in a refrigerator between 2°C and 8°C (36°F and 46°F). Do not freeze. Discard if frozen. Protect from light. After mixing, the vaccine may be stored under refrigeration between 2°C and 8°C (36°F and 46°F) or at room temperature up to 30°C (86°F) for up to 24 hours. Do not freeze. Discard if frozen. Protect from light.

Drug Interactions

Fingolimod: May diminish the therapeutic effect of Vaccines (Inactivated). Management: Vaccine efficacy may be reduced. Complete all age-appropriate vaccinations at least 2 weeks prior to starting fingolimod. If vaccinated during fingolimod therapy, revaccinate 2 to 3 months after fingolimod discontinuation. Consider therapy modification

Immunosuppressants: May diminish the therapeutic effect of Vaccines (Inactivated). Management: Complete all age-appropriate vaccinations at least 2 weeks prior to starting an immunosuppressant. If vaccinated less than 2 weeks before starting or during immunosuppressant therapy, revaccinate at least 3 months after immunosuppressant discontinuation. Consider therapy modification

Siponimod: May diminish the therapeutic effect of Vaccines (Inactivated). Management: Avoid administration of vaccines (inactivated) during treatment with siponimod and for 1 month after discontinuation due to potential decreased vaccine efficacy. Consider therapy modification

Venetoclax: May diminish the therapeutic effect of Vaccines (Inactivated). Monitor therapy

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

Actual percentages may vary by product and age group.


Dermatologic: Diaphoresis (6% to 11%)

Gastrointestinal: Abdominal pain (children and adolescents: ≤17%), anorexia (children and adolescents: 14% to 29%), change in appetite (infants and children: 18%), diarrhea (≤17%), nausea (≤17%), vomiting (children and adolescents: ≤17%)

Local: Erythema at injection site (≤34%), induration at injection site (≤15%), pain at injection site (36% to 83%), swelling at injection site (adults: ≤15%; infants, children, and adolescents: 28% to 29%), tenderness at injection site (adults: 70%; infants and children: 56%)

Nervous system: Drowsiness (infants and children: 25% to 38%), fatigue (20% to 34%), headache (3% to 35%), irritability (infants and children: ≤51%), malaise (16% to 25%), shivering (adults: 17%; children and adolescents: 4% to 10%)

Neuromuscular & skeletal: Arthralgia (10% to 25%), myalgia (9% to 45%)

Miscellaneous: Fever (3% to 22%), fussiness in an infant or toddler (≤51%)

1% to 10%:

Gastrointestinal: Gastroenteritis (children and adolescents: 1%)

Local: Itching at injection site (adults: 2%), warm sensation at injection site (adults: 1%)

Nervous system: Chills (older adults: 4%), dizziness (adults: 1%)


Dermatologic: Skin rash (adults)

Local: Bruising at injection site (adults)


Concerns related to adverse effects:

• Anaphylactoid/hypersensitivity reactions: Immediate treatment (including epinephrine 1 mg/mL) for anaphylactoid and/or hypersensitivity reactions should be available during vaccine use (ACIP [Ezeanolue 2020]).

• Shoulder injury related to vaccine administration: Vaccine administration that is too high on the upper arm may cause shoulder injury (eg, shoulder bursitis or tendinopathy) resulting in shoulder pain and reduced range of motion following injection. Use proper injection technique for vaccines administered in the deltoid muscle (eg, injecting in the central, thickest part of the muscle) to reduce the risk of shoulder injury related to vaccine administration (Cross 2016; Foster 2013).

• Syncope: Syncope has been reported with use of injectable vaccines and may be accompanied by transient visual disturbances, weakness, or tonic-clonic movements. Procedures should be in place to avoid injuries from falling and to restore cerebral perfusion if syncope occurs (ACIP [Ezeanolue 2020]).

Disease-related concerns:

• Acute illness: The decision to administer or delay vaccination because of current or recent febrile illness depends on the severity of symptoms and the etiology of the disease. Defer administration in patients with moderate or severe acute illness (with or without fever); vaccination should not be delayed for patients with mild acute illness (with or without fever) (ACIP [Ezeanolue 2020]).

• Bleeding disorders: Use with caution in patients with bleeding disorders (including thrombocytopenia); bleeding/hematoma may occur from IM administration; if the patient receives antihemophilia or other similar therapy, IM injection can be scheduled shortly after such therapy is administered (ACIP [Ezeanolue 2020]).

• Guillain-Barré syndrome: Use with caution in patients with a history of Guillain-Barré syndrome (GBS); patients with history of GBS have a greater likelihood of developing GBS than those without. Although data specific to the influenza A virus vaccine (H5N1) are unavailable, the following guidance is based on seasonal influenza vaccines: As a precaution, the Advisory Committee on Immunization Practices (ACIP) recommends that patients with a history of GBS and who are at low risk for severe influenza complications and patients known to have experienced GBS within 6 weeks following previous vaccination should generally not be vaccinated (consider influenza antiviral chemoprophylaxis in these patients). The benefits of vaccination may outweigh the potential risks in persons with a history of GBS who are also at high risk for complications of influenza (CDC/ACIP [Grohskopf 2019]). Studies of patients who received the trivalent inactivated influenza vaccine or the monovalent H1N1 influenza vaccine have shown the risk of GBS is lower with vaccination than with influenza infection (Baxter 2013; Greene 2013; Kwong 2013).

Concurrent drug therapy issues:

• Anticoagulant therapy: Use with caution in patients receiving anticoagulant therapy; bleeding/hematoma may occur from IM administration (ACIP [Ezeanolue 2020]).

• Vaccines: In order to maximize vaccination rates, the ACIP recommends simultaneous administration (ie, >1 vaccine on the same day at different anatomic sites) of all age-appropriate vaccines (live or inactivated) for which a person is eligible at a single clinic visit, unless contraindications exist. The ACIP prefers each dose of a specific vaccine in a series come from the same manufacturer when possible; however vaccination should not be deferred because a specific brand name is unavailable (ACIP [Ezeanolue 2020]).

Special populations:

• Altered immunocompetence: Consider deferring immunization during periods of severe immunosuppression (eg, patients receiving chemo/radiation therapy or other immunosuppressive therapy [including high-dose corticosteroids]); may have a reduced response to vaccination. In general, household and close contacts of persons with altered immunocompetence may receive all age appropriate vaccines. Inactivated vaccines should be administered ≥2 weeks prior to planned immunosuppression when feasible; inactivated vaccines administered during chemotherapy should be readministered after immune competence is regained (ACIP [Ezeanolue 2020]; IDSA [Rubin, 2014]).

• Elderly: Sanofi Pasteur product has not been evaluated in patients ≥65 years of age

• Pediatric: Apnea has occurred following intramuscular vaccine administration in premature infants; consider clinical status implications. In general, preterm infants should be vaccinated at the same chronological age as full-term infants (ACIP [Ezeanolue 2020]).

Dosage form specific issues:

• Chicken egg protein: Product may be manufactured with chicken egg protein.

• Thimerosal: Product may contain thimerosal; hypersensitivity reactions may occur.

Other warnings/precautions:

• Antipyretics: Antipyretics have not been shown to prevent febrile seizures; antipyretics may be used to treat fever or discomfort following vaccination (ACIP [Ezeanolue 2020]). One study reported that routine prophylactic administration of acetaminophen prior to vaccination to prevent fever decreased the immune response of some vaccines; the clinical significance of this reduction in immune response has not been established (Prymula 2009).

• Effective immunity: Vaccination may not result in effective immunity in all patients. Response depends upon multiple factors (eg, type of vaccine, age of patient) and may be improved by administering the vaccine at the recommended dose, route, and interval. Vaccines may not be effective if administered during periods of altered immune competence (ACIP [Ezeanolue 2020]).

Monitoring Parameters

Monitor for anaphylaxis and syncope for 15 minutes following administration (ACIP [Ezeanolue 2020]). If seizure-like activity associated with syncope occurs, maintain patient in supine or Trendelenburg position to reestablish adequate cerebral perfusion.

Pregnancy Risk Factor C (Sanofi Pasteur product) Pregnancy Considerations

Adverse events were not observed in animal reproduction studies using the H5N1 vaccine GlaxoSmithKline adjuvanted product; animal reproduction studies have not been conducted with the Sanofi Pasteur product. Inactivated viral vaccines have not been shown to cause increased risks to the fetus (ACIP [Ezeanolue 2020]).

Patient Education

What is this drug used for?

• It is used to prevent the flu caused by the influenza A (H5N1) virus.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Headache

• Loss of strength and energy

• Shivering

• Sweating

• Muscle pain

• Joint pain

• Fatigue (children)

• Fussiness (children)

• Lack of appetite (children)

• Nausea (children)

• Vomiting (children)

• Diarrhea (children)

• Abdominal pain (children)

• Injection site pain, redness, or swelling

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Burning or numbness

• Facial muscle rigidity

• Trouble moving

• Severe dizziness

• Passing out

• Muscle weakness

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.