Immunogenicity and safety of seasonal influenza vaccines in children under 3 years of age

ABSTRACT

Introduction

Despite children aged 6–35 months developing more severe influenza infections, not all countries include influenza vaccines in their national immunization programs.

Areas covered

This literature review examines the efficacy, immunogenicity, and safety of seasonal trivalent influenza vaccines (TIVs) and quadrivalent influenzae vaccines (QIVs) in children 6–35 months old to determine if greater valency promotes greater protection while maintaining a similar safety profile.

Expert opinion

TIVs and QIVs are safe for children under 3 years old. TIVs and QIVs provided good seroprotection, and immunogenicity (GMT, SCR, and SPR) meeting recommended levels set by CHMP (European) and CBER (USA). However, as QIVs carry two influenza B strains and TIVs only one, QIVs has an overall higher seroprotection against particularly influenza B. Vaccines containing adjuncts had better immunogenicity, particularly after the first dose. Seroprotection of all vaccines lasted 12 months. Increasing the dosage from 0.25 mL to 0.5 mL did not cause more systemic or local side-effects. Further comparisons of efficacy, and wider promotion of influenza vaccines in general are required in preschool children.

KEYWORDS:

• Immunogenicity
• vaccine efficacy
• safety
• trivalent influenza vaccine
• quadrivalent influenza vaccine

Article highlights

• Two vaccine types are available to protect against seasonal influenza caused by influenza A and B. This systemic literature review compared trivalent (TIV) and quadrivalent (QIV) vaccine immunogenicity and safety in children under 3 years of age.

• Twenty-three articles were identified of which 11 discussed efficacy, 15 immunogenicity, and 18 safety of seasonal influenza vaccines.

• TIVs and QIVs are effective, immunogenic, and safe in children aged 6–35 months.

• QIVs have wider coverage of Influenza B strains than TIVs, as they include two major lineages (B/Yamagata and B/Victoria) compared to TIVs, which carry a single lineage.

• Healthy children 6–35 months old have relatively low vaccination rates due to their exclusion from national vaccination programs and the lack of widespread knowledge on vaccine safety and efficacy.

Declaration of interest

R Borrow performs contract research on behalf of UK Health Security Agency for GSK, Pfizer, and Sanofi Pasteur. The authors have no other 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 apart from those disclosed.

Reviewer disclosures

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

Additional information

Funding

This paper was not funded.