Adjuvanted influenza vaccines

Abstract

Influenza is one of the most common causes of human morbidity and mortality that is preventable by vaccination. Immunization with available vaccines provides incomplete protection against illness caused by influenza virus, especially in high-risk groups such as the elderly and young children. Thus, more efficacious vaccines are needed for the entire population, and all the more so for high-risk groups. One way to improve immune responses and protection is to formulate the vaccine with antigen carriers and/or adjuvants, which can play an important role in improving immune responses and delivery to antigen-presenting cells, especially for a vaccine like influenza that is based on protein antigens usually administered without a carrier or adjuvant. In this review, the authors present an overview of available vaccines, focusing on research and development of new adjuvants used in influenza vaccines, as well as adjuvanted influenza vaccines aimed to improve immune responses, protection and breadth of coverage for influenza.

Intranasal Inactivated Influenza Vaccines: a Reasonable Approach to Improve the Efficacy of Influenza Vaccine?

“…Thus, safer adjuvants for clinical use as nasal vaccine adjuvants are required, and many adjuvants are currently being development to improve influenza vaccine efficacy (15,64). We note the usefulness of synthetic RNA poly (I:C), a ligand for TLR 3, as a nasal vaccine adjuvant instead of CT or LT-related materials (15,65,66).…”

Infants and the seasonal influenza vaccine

“…19,20,21,22 Among the general population, the seasonal influenza vaccine is not as effective as many other vaccines, with a mean efficacy in adults of about 60%, and the immunity is reduced within months. 25 Using adjuvants have the potential to augment the length and strength of immunity induced by the vaccine, but potential safety concerns prevent clinical trials and approval of many adjuvants. MF59, an oil-in-water emulsion adjuvant is found to enhance immunogenicity and used in influenza vaccines made for the elderly.…”

“…27 Virosome adjuvants are approved in one vaccine in the United States (Inflexal V), and two adjuvants, AS03 and Aluminum phosphate, are used in pandemic influenza vaccines in Europe. 25 A Phase II clinical trial was completed in 2012 to explore the immunogenicity and safety of MF59C.1-adjuvanted influenza vaccine (currently used in the elderly population) in infants aged 6 to 36 mo in Belgium. 28,29 There are several adjuvants being investigated for potential use in seasonal influenza vaccines to be used for different age groups, including the use of liposomes as adjuvants in virosomal vaccines.…”

“…Studies that demonstrate efficacy of adjuvants in children 6 mo cannot necessarily be extrapolated to children <6 mo due to the frequent changes in immune responses in early life. Adjuvants are potential solutions to inducing the protective response in infants, 25 but the widespread fear of adverse events from adjuvants that persist in popular media may be a hindrance for vaccine acceptance even if it is approved. 31 Using the intradermal route rather than the intramuscular route with current vaccine formulations in infants under six months of age could possibly induce a sufficient immune response as opposed to the intramuscular route.…”

In Silico Analysis of HA2/Mx Chimera Peptide for Developing an Adjuvanted Vaccine to Induce Immune Responses Against Influenza Viruses

“…The molecules act by different mechanisms include prolonging the exposure time of antigen to the immune system, enhancing the delivery of antigen, directing antigen presentation by the MHC, or providing immune stimulatory signals that potentiate the immune response. [18][19][20] The ability of molecular adjutants such as cytokines, bacterial derivatives and immune system regulator proteins to improve the immunogenicity of vaccines as a novel strategy is under evaluation. [21][22][23][24][25][26] Here we explore the idea of using host cellular protein to elicit immune responses against influenza virus and choose Mx protein which belongs to the class of dynamin-like large guanosine triphosphatases (GTPases) and involves in interferon induction and immune system regulation.…”