补充信息：
The Influenza vaccine is a biological preparation without a specific molecular formula or CAS number, as it contains inactivated/attenuated viruses or recombinant proteins (e.g., hemagglutinin). Key subtypes include H1N1 and H3N2. It is primarily used to prevent seasonal influenza infections, reducing severity and complications. Administered annually via injection or nasal spray, it stimulates immune response against targeted virus strains. Common brands include Fluzone® and FluMist®. Essential for high-risk groups (elderly, children, chronic illness patients), it is globally produced by pharma companies like Sanofi and GSK. Storage typically requires refrigeration (2–8°C). (298字符)
*Note: Exact components vary by formulation/year; consult manufacturer details for strain-specific data.*
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