Injectable Excipients as Novel Influenza Vaccine Adjuvants.

Area of Science:

• Immunology
• Vaccinology
• Pharmacology

Background:

• Influenza outbreaks necessitate effective vaccination strategies.
• Current inactivated influenza vaccines show suboptimal efficacy, particularly in elderly populations.
• Adjuvants can improve vaccine efficacy, but approved options for human use are limited.

Purpose of the Study:

• To identify novel, safe, and effective adjuvants for influenza vaccines.
• To screen injectable drug additives approved in Japan for adjuvant potential.
• To evaluate the efficacy of identified compounds in enhancing split influenza hemagglutinin (HA) vaccine effectiveness.

Main Methods:

• A mouse model was utilized to screen 46 injectable drug additives approved in Japan.
• The efficacy of the split influenza HA vaccine was assessed with and without the addition of candidate compounds.
• Compounds were evaluated based on their ability to enhance vaccine protection against lethal influenza virus challenge.

Main Results:

• Twenty out of 46 screened compounds demonstrated enhanced efficacy of the split influenza HA vaccine.
• These 20 compounds included 15 novel adjuvant candidates and 5 with previously reported adjuvant effects for other antigens.
• The identified compounds are already approved for human use, suggesting a lower regulatory hurdle for clinical application.

Conclusions:

• Several injectable drug additives approved in Japan show promise as novel adjuvants for influenza vaccines.
• The existing approval status of these compounds facilitates their potential clinical translation.
• This study provides a valuable resource for developing improved influenza vaccines with enhanced efficacy, especially for vulnerable populations.