Novel Influenza Vaccine Induces Immunity Throughout Flu Season: Presented at ESPID

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Title: Novel Influenza Vaccine Induces Immunity Throughout Flu Season: Presented at ESPID
URL: http://www.pslgroup.com/dg/221E62.htm
Doctor's Guide
May 23, 2008

By Neil Osterweil

GRAZ, Austria -- May 23, 2008 -- A novel adjuvanted influenza vaccine continues to induce significantly higher immune responses in unprimed healthy children than the conventional split vaccine, researchers reported here at the 26th Annual Meeting of the European Society for Paediatric Infectious Diseases (ESPID).

Timo Vesikari, MD, Professor, University of Tampere Medical School, Tampere, Finland, and colleagues both at his institution and at Novartis Vaccines in Italy and Germany performed an extended follow-up of 6 months on a randomised, observer-blinded, multicentre trial.

The trial, presented on May 14, compared the reactogenicity, safety, and immunogenicity of 2 intramuscular doses of the 2006/2007 NH formulation of an MF59 adjuvanted influenza subunit vaccine to a conventional split vaccine

A total of 269 healthy children aged 6 months to under 3 years were randomised on a 1:1 basis to receive either the subMF59 vaccine or the split vaccine before the 2006/2007 winter flu season. Each vaccine contained the 3 influenza strains recommended for coverage: A/New Caledonia/20/99 (H1N1)-like, A/Wisconsin/67/2005 (H3N2)-like, and B/Malaysia/2506/2004-like.

The authors evaluated immunogenicity by a haemagglutination inhibition assay after each dose and at the end of 6 months' follow-up, using geometric mean titres and their corresponding 95% confidence intervals, geometric mean ratio of pre- to postvaccination titres, and seroprotection rate (defined as the percentage of children with haemagglutination inhibition titres of 40 or higher).

Safety was evaluated with solicited local and systemic reactions within 7 days of each vaccine dose, as well as the local reactions recorded in parent diaries. All adverse events were recorded from the first dose until 3 weeks after the second dose.

The investigators found that both vaccines were safe, and that there were no excess adverse events reported for the sub/MF59 group over the 6-month follow-up. Probable or possible vaccine-related adverse events occurred in 21 children in each vaccine group.

Eight serious adverse events were recorded, 2 among children who received the split vaccine, and 6 among children who received the sub/MF59, but none of these events were deemed to be related to the vaccines.

For both vaccines, the immune responses were strongest against the A/H3N2 strain, followed by A/H1N1 and the B strain. Following the first dose, the sub/MF59 vaccine induced significantly higher (P < .001) seroprotection rates against the A/H3N2 and A/H1N1 strains.

Three weeks after the second dose, 99% of children in the sub/MF59 group had achieved seroprotection against the B strain, compared with 33% of children in the split vaccine group (P < .001).

All titres declined over the 6-month period, but remained consistently higher in the sub/MF59 vaccinated children. At 6 months, seroprotection rates for sub/MF59 were 100% against H3N2, 48% against H1N1 and 22% against the B strain. In contrast, seroprotection rates at 6 months for the split vaccine were 66% against H3N2, 20% against H1N1, and 3% against the B strain (P < .001 for all vs the sub/MF59 vaccine).

The authors concluded that in vaccine-naive children, the sub/MF59 adjuvanted influenza vaccine was safe, and induced significantly higher immune responses than a conventional vaccine throughout an influenza epidemic season.

This study was funded by Novartis Pharma AG.

[Presentation title: MF59 Adjuvanted Influenza Vaccine (Fluad): Sustained Immunogenicity Over Influenza Epidemic Season in Unprimed Healthy Children. Abstract 664]

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