A pilot trial of Novartis adjuvanted cell culture-based A(H1N1) vaccine indicates that the 'swine flu' vaccine elicited a strong immune response and was well tolerated. The trial was run by the UK's University of Leicester and University Hospitals of Leicester. The vaccine, to be called Celtura, was tested with 100 healthy volunteers, aged between 18 and 50.

The trial evaluated the tolerability and immunogenicity of the vaccine. Different schedules and timing between vaccinations were tested. The vaccine schedule comprised one or two doses of 7.5µg MF-59 adjuvanted surface-antigen A/California/2009 vaccine derived from cell-culture. Results showed that the serum antibody responses were highest among subjects who received two doses of vaccine, however a single vaccine dose also induced responses associated with protection against influenza.

Haemagglutination-inhibition titres reached 1:40 or greater in 80 per cent and more than 90 per cent of those receiving one dose and two doses respectively. These would satisfy the immunogenicity criteria as set out by European and US regulators. The findings showed that it is possible to induce protective antibodies against A(H1N1) infection within two weeks of administration of a single low-dose adjuvanted vaccine. Non-adjuvanted formulations were not evaluated in the study.

Additional pivotal clinical trials, with larger numbers of subjects and sponsored by Novartis, are already under way around the world. They will include more than 6000 adults and children.

"The pilot trial results are encouraging," said Dr Andrin Oswald, CEO of Novartis Vaccines and Diagnostics. "The study suggests that while two doses seem to provide better protection, one dose of our adjuvanted Celtura vaccine may be sufficient to protect adults against the swine flu. This is important information for public health authorities who prepare for vaccination in the coming months with limited vaccine supply."

The pilot trial was led by Dr Stephenson of the Department of Infection, Immunity and Inflammation at the University of Leicester. He is a clinical senior lecturer at the University, and a consultant in infectious diseases at the University Hospitals of Leicester NHS Trust. Dr Stephenson said, "The aim of the trial was to find out how many doses and what type of vaccine is needed to give protection. These initial results should help to plan vaccination campaigns in the autumn, including doses and timings. We concluded that the MF59-adjuvanted A(H1N1) vaccine of low antigen content was well tolerated and generated antibody responses associated with protection against influenza, even after a single dose."