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Enhanced immunogenicity of seasonal influenza vaccines in young children using MF59 adjuvant
Timo Vesikari1, Michele Pellegrini, Aino Karvonen
1Vaccine Research Center, University of Tampere Medical School, Tampere, Finland. Timo.Vesikari@uta.fi
Insights
MF59-adjuvanted influenza vaccines show improved efficacy in young children compared to conventional vaccines. This adjuvanted vaccine offers greater, longer-lasting, and broader immune protection against seasonal influenza.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Children experience high rates of influenza-related illness and hospitalization.
- Conventional inactivated influenza vaccines demonstrate low efficacy in young children.
- Adjuvanted influenza vaccines are being investigated to enhance protection in this population.
Purpose of the Study:
- To evaluate the safety and immunogenicity of an MF59-adjuvanted influenza vaccine in young children.
- To compare the immune response elicited by the adjuvanted vaccine versus a nonadjuvanted split vaccine.
Main Methods:
- An observer-blinded study enrolled healthy children aged 6 to <36 months.
- Participants received two doses of either MF59-adjuvanted or nonadjuvanted split influenza vaccine.
- Hemagglutination inhibition antibody titers were measured post-vaccination, with a subset receiving a booster dose.
Main Results:
- Both vaccines were generally comparable in safety and tolerability.
- The MF59-adjuvanted vaccine induced significantly higher antibody titers against all vaccine strains.
- Enhanced cross-reactivity against mismatched influenza strains was observed with the adjuvanted vaccine.
Conclusions:
- MF59-adjuvanted influenza vaccine is well-tolerated and induces superior immune responses in young children.
- The adjuvanted vaccine provides greater, longer-lasting, and broader protection compared to the nonadjuvanted vaccine.
- Enhanced immunogenicity was particularly noted in very young children and against the B vaccine strain.
Background:
Children have high morbidity and hospitalization rates from seasonal influenza. Meta-analyses suggest that conventional inactivated influenza vaccines are of low efficacy in young children, making vaccines that induce greater and broader immune protection in this vulnerable population a medical priority. Adjuvanted influenza vaccines may offer a solution.
Subjects And Methods:
Unprimed healthy children (6 to <36 months) were enrolled in an observer-blinded study and randomly assigned to receive 2 doses of MF59-adjuvanted vaccine (Sub/MF59, n = 130) or nonadjuvanted split vaccine (split, n = 139); subgroups of these (n = 43 and 46, respectively) received a booster dose 1 year later. Safety and clinical tolerability were assessed after each dose. Hemagglutination inhibition antibody titers were measured against influenza A and B strains included in the formulation of the vaccines and against mismatched strains.
Results:
Clinical tolerability and safety were generally comparable between vaccine groups, though some transient, mild solicited reactions were more frequent in the Sub/MF59 group. Postvaccination hemagglutination inhibition antibody titers to all 3 vaccine strains were significantly higher with Sub/MF59 than with split vaccine (all comparisons P < 0.001) after each of the 3 vaccine doses. In addition, Sub/MF59 induced significantly higher cross-reactivity against A/H3N2 and A/H1N1 mismatched strains.
Conclusion:
MF59-adjuvanted influenza vaccine was well tolerated in healthy young children after each of 3 doses and induced greater, longer-lasting, and broader immune responses than a nonadjuvanted split vaccine. The enhanced immunogenicity of the adjuvanted vaccine was most evident in very young children and for the B vaccine strain.
