Pandemic Influenza Vaccine H5n1 Astrazeneca (A/Vietnam/1203/2004 (H5n1) Strain (A/Vietnam/1203/2004, Medi 0141000136))

Pandemic Influenza Vaccine H5n1 Astrazeneca is used within the influenza vaccine family to prevent infection by the H5N1 avian influenza virus.

• Pandemic H5N1 influenza: Provides prophylactic immunity against infection with the H5N1 virus in adults.
• High‑risk occupational exposure: Protects healthcare workers and laboratory personnel who may encounter H5N1.
• Travel to endemic regions: Reduces risk of acquiring H5N1 for travelers to areas with confirmed avian influenza activity.
• Outbreak control: Supports public‑health measures during H5N1 outbreaks by immunising at‑risk populations.
• Vaccination of close contacts: Helps limit spread among family members of infected individuals.

• The vaccine contains inactivated A/Vietnam/1203/2004 (H5N1) virus particles that present hemagglutinin antigens to the nasal mucosa. Upon administration, antigen‑presenting cells capture the viral proteins and stimulate B‑cell and T‑cell responses, leading to the production of neutralising antibodies that block viral attachment and entry, thereby conferring protective immunity. The mucosal route also induces local IgA antibodies, enhancing barrier protection in the respiratory tract.

Administration of the nasal H5N1 vaccine may be associated with a range of adverse reactions, most of which are mild and transient.

Common Side Effects

• Nasal congestion: mild blockage or stuffiness in the nose.
• Sore throat: irritation or discomfort in the throat.
• Low‑grade fever: temperature rise up to 38 °C.
• Headache: mild to moderate head pain.
• Runny nose: watery nasal discharge.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurologic disorder causing muscle weakness.
• Severe respiratory distress: difficulty breathing or wheezing.
• High fever: temperature above 39 °C persisting more than 24 hours.
• Neurologic events: seizures or altered consciousness.

Before prescribing Pandemic Influenza Vaccine H5n1 Astrazeneca, healthcare professionals should consider the following precautions.

• Pregnancy: safety not established; use only if potential benefits justify the risk.
• Breastfeeding: limited data; evaluate risk‑benefit before administration.
• Immunocompromised patients: may exhibit reduced immune response to the vaccine.
• Known hypersensitivity: avoid in individuals allergic to any vaccine component.
• Age restrictions: not recommended for children under 18 years of age.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

The nasal H5N1 vaccine can interact with other medicines or vaccines; relevant interactions are listed below.

Major Interactions (Avoid)

• Live attenuated vaccines: concurrent use may diminish effectiveness of either product.
• Immunosuppressive therapy: may markedly reduce vaccine‑induced immunity.
• Antiviral agents (e.g., oseltamivir): can interfere with the development of protective antibodies.

Moderate Interactions (Monitor Closely)

• Antipyretic medications: may mask post‑vaccination fever, obscuring assessment.
• Other inactivated influenza vaccines: schedule at least 14 days apart to avoid immune interference.
• Allergy medications (antihistamines): generally safe but monitor for altered local reactions.