Comparative immunogenicity of several inactivated influenza vaccines among healthcare workers in Hong Kong

Among adult healthcare workers in Hong Kong during the 2025/26 season, three licensed egg-based inactivated influenza vaccines produced broadly comparable immune responses, including similar fold-rises and seroconversion rates.

• Why it matters: Seasonal vaccination programs need evidence that different licensed inactivated products generate comparable immunogenicity in real-world recipients, especially for healthcare workers.
• What they did: In an ongoing Hong Kong cohort, age- and sex-matched adults (n=30-40 per group) received TetrAnflu, Fluarix Tetra, or Vaxigrip, and paired pre/post sera were tested by hemagglutination-inhibition against 2025/26 egg-propagated reference strains.
• The result: The vaccines showed broadly comparable geometric mean fold-rises, post-vaccination titers, proportions with titers >=40, and seroconversion rates, supporting interchangeability for seasonal influenza vaccination programs in this group.

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