Pediatric influenza immunization

Advax™, a polysaccharide adjuvant derived from delta inulin, provides improved influenza vaccine protection through broad-based enhancement of adaptive immune responses

Advax™ adjuvant is derived from inulin, a natural plant-derived polysaccharide that when crystallized in the delta polymorphic form, becomes immunologically active. This study was performed to assess the ability of Advax™ adjuvant to enhance influenza vaccine immunogenicity and protection. Mice were immunized with influenza vaccine alone or combined with Advax™ adjuvant. Immuno-phenotyping of the anti-influenza response was performed including antibody isotypes, B-cell ELISPOT, CD4 and CD8 T-cell proliferation, influenza-stimulated cytokine secretion, DTH skin tests and challenge with live influenza virus. Advax™ adjuvant increased neutralizing antibody and memory B-cell responses to influenza. It similarly enhanced CD4 and CD8 T-cell proliferation and increased influenza-stimulated IL-2, IFN-γ, IL-5, IL-6, and GM-CSF responses. This translated into enhanced protection against mortality and morbidity in mice. Advax™ adjuvant provided significant antigen dose-sparing compared to influenza antigen alone. Protection could be transferred from mice that had received Advax™-adjuvanted vaccine to naïve mice by immune serum. Enhanced humoral and T-cell responses induced by Advax™-formulated vaccine were sustained 12months post-immunization. Advax™ adjuvant had low reactogenicity and no adverse events were identified. This suggests Advax™ adjuvant could be a useful influenza vaccine adjuvant.

Febrile events including convulsions following the administration of four brands of 2010 and 2011 inactivated seasonal influenza vaccine in NZ infants and children: the importance of routine active safety surveillance

OBJECTIVE

To evaluate and compare rates of febrile events, including febrile convulsion, following immunisation with four brands of inactivated 2010 and 2011 influenza vaccine in NZ infants and children.

DESIGN

Retrospective telephone surveys of parents of infants and children who received at least one dose of the vaccines of interest.

SETTING

184 NZ General Practices who received the vaccines of interest.

PARTICIPANTS

Recipients of 4088 doses of trivalent inactivated vaccines Fluvax(®), Vaxigrip(®), Influvac(®) and Fluarix(®) and/or monovalent Celvapan. Vaccinees were identified via the electronic Practice Management System and contacted consecutively.

MAIN OUTCOME MEASURES

Primary outcome was febrile convulsive seizure. Secondary outcomes were presence of fever plus other organ system specific symptoms.

RESULTS

The parental response rate was 99%. Of 4088 doses given, 865 were Fluvax(®), 2571 Vaxigrip(®), 204 Influvac(®), 438 Fluarix(®) and 10 Celvapan. Three febrile convulsions followed Fluvax(®), a rate of 35 per 10,000 doses. No convulsions occurred following any dose of the other vaccines. There were nine febrile events that included rigors, all following Fluvax(®). Fever occurred significantly more frequently following administration of Fluvax(®) compared with the other brands of vaccines (p<0.0001) and Fluvax recipients were more likely to seek medical attention. Influvac(®) also had higher rates of febrile reactions (OR 0.54, 0.36-0.81) than the other two brands Vaxigrip(®) (OR 0.21, 0.16-0.27) and Fluarix(®) (OR 0.10, 0.05-0.20). After multivariable analysis vaccine, European ethnicity and second dose of vaccine were significantly associated with reporting of fever within 24h of vaccination.

CONCLUSIONS

Influenza vaccines have different rates of reactogenicity in children which varies between ethnic groups. High rates of febrile convulsions and reactions in children receiving Fluvax(®) and to a lesser extent the higher fever rates in those receiving Influvac(®) compared with the other two brands of influenza vaccines in this study suggests that reactogenicity profiles need to be considered prior to national policy advice each season. The risk-benefit profile in children might not be equally favourable for all licensed paediatric influenza vaccines. More attention needs to be given to comparative research for all trivalent seasonal vaccines, and with all strain changes.