Intake of Korean Red Ginseng Extract and Saponin Enhances the Protection Conferred by Vaccination with Inactivated Influenza A Virus

Vaccination is the main strategy for preventing influenza infection. However, vaccine efficacy is influenced by several factors, including age and health status. The efficacy of the influenza vaccine is much lower (17% to 53%) in individuals over 65 yr of age compared with young adults (70% to 90%). Therefore, increasing vaccine efficacy remains a challenge for the influenza vaccine field. In this study, we investigated the impact of supplementing vaccination with the dietary intake of Korean red ginseng (RG) extract and RG saponin. Mice were immunized two times intranasally with inactivated influenza A (H1N1) virus. Mice received RG extract or RG saponin orally for 14 d prior to the primary immunization. After the primary immunization, mice continued to receive RG extract or RG saponin until the secondary immunization. Mice vaccinated in combination with dietary intake of RG extract and RG saponin showed elevated serum anti-influenza A virus IgG titers and improved survival rates in lethal influenza A virus infection: 56% and 63% of mice receiving RG extract or RG saponin survived, respectively, while 38% of mice that only received the vaccine survived. Moreover, mice receiving RG extract supplementation recovered their body weight more quickly than those not receiving RG extract supplementation. We propose that the dietary intake of RG extract and RG saponin enhances the vaccine-induced immune response and aids in providing protection against influenza virus infection.