July 02, 2014
2 min read

Seasonal influenza vaccine promoted antibody persistence in young children

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Recent data showed that the investigational, egg-derived, monovalent, MF59-adjuvanted, seasonal influenza vaccine allowed reduced antigen content and promoted significant long-term antibody persistence among children aged 6 to 35 months.

Markus Knuf, MD, of the University of Medicine in Rheinland-Pfalz, Germany, and colleagues randomly assigned 144 children, aged 6 to 11 months, and 186 children, aged 12 to 35 months, to vaccine formulations containing 3.75 mcg antigen with half of the standard dose of MF59 (Focetria, Novartis), 7.5 mcg antigen with a standard dose of MF59 or a non-adjuvanted formulation containing 15 mcg antigen (only administered to the older age group). Study participants were given two primary vaccine doses 3 weeks apart, followed by one booster dose of MF59-adjuvanted seasonal influenza vaccine a year later. The study was conducted across 18 sites in Germany, Belgium, the Netherlands, the Dominican Republic and Chile between September 2009 and July 2011.

Among the younger age group, those who received full doses of MF59 had greater geometric mean titers compared with those who received half the standard dose, according to the researchers. One dose of either MF59 met the European Union’s Committee for Medicinal Products for Human Use criteria for geometric mean ration.

Among the older age group, full doses of MF59 induced greater geometric mean titers than half doses. Geometric mean titers were greater in response to both dosages of MF59 compared with the non-adjuvanted formulation.

All three vaccines met licensure criteria for geometric mean rations as early as 3 weeks after the first vaccination, according to the study results.

Regarding seroconversion, children in the younger age group had high hemagglutination seroconversion rates for both formulations after first and second vaccinations. Those in the older age group who received adjuvanted formulations experienced these same rates. Seroconversion rates were lower among children who received non-adjuvanted formulation than those who received adjuvanted formulations. For both age groups, seroconversion rates were more than 40% for all vaccines after first and second vaccinations; and thus were above the Committee for Medicinal Products for Human Use licensure requirements, according to the researchers.

Long-term antibody persistence was observed in children who received MF59-adjuvanted vaccines.

Erythema and tenderness were the most frequently reported local reactions after primary immunization. Local reactions were generally more frequent after the booster dose than primary doses. Tenderness was most frequently reported after the booster dose and second seasonal dose, followed by erythema. There were three reports of fever higher than 40°C, two in the younger age group and one in the older age group, all following the first vaccination.

“A single dose of 3.75 mcg antigen together with half the standard dose of MF59 was identified as optimal, provided adequate levels of immediate and long-term antibodies and an acceptable safety profile in children 6 to 35 months of age. These data support the suitability of MF59-adjuvanted vaccines for pandemic immunization in the pediatric population,” the researchers concluded.

Disclosure: Some of the researchers have financial ties with AstraZeneca, GlaxoSmithKline, Immune Targeting Systems, Novartis and Wyeth/Pfizer. Five of the researchers are permanent employees of Novartis Vaccines and Diagnostics, which funded the study.