Understanding immunity to influenza: implications for future vaccine development

ABSTRACT

Introduction

Influenza virus changes its genotype through antigenic drift or shift making it difficult to develop immunity to infection or vaccination. Zoonotic influenza A virus (IAV) strains can become established in humans. Several impediments to human infection and transmission include sialic acid expression, host anti-viral factors (including interferons), and other elements that govern viral replication. Controlling influenza infection, replication, and transmission is important because IAVs cause annual epidemics and occasional pandemics. Effective seasonal influenza vaccines exist, but these vaccines do not fully protect against novel or pandemic strains.

Areas covered

With new vaccine production technology, vaccines can be produced rapidly. Universal IAV vaccines are being developed to protect against seasonal, novel, and zoonotic IAVs. These efforts are being enhanced and accelerated by a better understanding the host immune response to influenza viruses.

Expert opinion

This review discusses several implications for future influenza vaccine development. Host immune responses to influenza virus infection or vaccination can guide vaccine development as anti-influenza immunity is affected by responses influenced by the previous immune history including first and subsequent exposures to influenza virus infections and vaccinations.

KEYWORDS:

• Influenza
• immunity
• host immunity
• vaccines
• human

Article highlights

• Influenza disease is vaccine-preventable.

• Influenza vaccines need yearly reformulation and come with variable vaccine efficacy.

• Influenza vaccines may contribute to reductions in influenza morbidity and mortality.

• Influenza vaccines have limited effectiveness in part due to antigenic evolution and immune imprinting.

• Influenza vaccines predominantly use embryonated chicken eggs for vaccine production.

• Alternative influenza vaccine approaches are being investigated to try to induce more robust and longer-lasting immune responses with the hope of overcoming antigenic drift, immune imprinting, and addressing the potential of emerging/novel influenza viruses.

• New approaches are being examined to boost innate and/or adaptive immunity and to improve vaccine-induced immune responses in individuals with diminished immunity, including older adults.

• Evidence indicates that universal influenza vaccine efficacy will be difficult if not unachievable.

• mRNA influenza vaccines could become an armament for universal influenza vaccines.

Declaration of interests

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or material discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or mending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Author contribution

Ralph Tripp contributed to the conception, review, interpretation of the relevant literature, and writing/revision of the article.

Additional information

Funding

This manuscript was funded in part by the Georgia Research Alliance.