GlaxoSmithKline Biologicals announced that Daronrix, its first generation alum-adjuvanted inactivated whole virus candidate flu vaccine for use once a pandemic has officially been declared by the WHO/EU, has received a positive opinion from Europe's Committee for Medicinal Products for Human Use (CHMP). This is a first step in the preparation against a possible H5N1 pandemic.

GSK will submit a second file to the European Regulatory Authorities within the next few weeks for its second generation H5N1 candidate vaccine. This vaccine, which is currently in late-stage development, utilises GSK's novel proprietary adjuvant system technology. Upon licensure, this second vaccine could potentially be used as part of a proactive pre-pandemic vaccination campaign, helping to prepare the human immune system in advance of a pandemic and give broad protection against different H5N1 strains.

This new generation vaccine candidate could also be adapted for use as a pandemic vaccine once the flu strain causing the pandemic has been identified. It also has the added benefit of requiring a substantially lower amount of antigen to raise a strong immune response and gives the ability to produce very large quantities of vaccines for mass vaccination, a GSK press release stated.

Jean Stéphenne, president of GSK Biologicals, the vaccine division of GSK, said: "Receiving this positive opinion today from the CHMP is testament to the company's ongoing commitment to provide health authorities with concrete options against the threat of an influenza pandemic. I believe, with the imminent filing of our second generation vaccine GSK has brought two solid vaccine solutions to prepare for pandemic or proactive pre-pandemic vaccination."

The submission dossier for the first generation vaccine, which received the positive opinion today, was based on a series of data including a pivotal clinical trial involving 400 healthy adults1. This trial evaluated the safety, reactogenicity and immunogenicity of different doses of the candidate vaccine and compared it to different doses of non-adjuvanted H5N1 influenza vaccine. It was concluded from the study, that two doses containing at least 15mg of H5N1 HA antigen are required to meet the EMEA's (European Medicines Agency) licensing criteria for seroprotection rate (SP³70%), seroconversion rate (SC³40%) and seroconversion factor (2.5). The vaccine also had a safety and reactogenicity profile similar to non-adjuvanted vaccine1.

GSK's proprietary-adjuvanted second generation (pre-) pandemic vaccine, which the company expects to file shortly, requires significantly less antigen (3.8mg) to meet the EMEA's licensing criteria2. This marked reduction in the amount of antigen required to obtain a strong immunogenic response (the so-called 'antigen-sparing' phenomenon) should allow more people to be vaccinated in the event of a pandemic.