GlaxoSmithKline (GSK) announced that the European Committee for Medicinal Products for Human Use (CHMP) has issued a positive opinion and recommends approval of GSK's candidate pandemic (H1N1) adjuvanted vaccine Pandemrix. The indication for the vaccine is for protection against pandemic H1N1 2009 influenza.

Each single dose of the vaccine will comprise 3.75ug antigen of pandemic (H1N1) 2009 influenza strain and GSK's proprietary adjuvant system AS03, which should be administered as two single doses at least three weeks apart.

"This positive opinion means that Pandemrix will now be immediately reviewed for approval by the European Commission which is an important step closer to helping reduce the impact of the pandemic. GSK will continue to work closely with regulators, governments and health authorities around the world so that they can determine the most appropriate strategy to address the H1N1 pandemic," said Jean Stéphenne, president GSK Biologicals.

The positive opinion is based on the 'mock-up' Pandemrix registration file using the H5N1 antigen which was approved in Europe in May 2008. The file included data from numerous clinical and pre-clinical trials which evaluated tolerability, reactogenicity, immunogenicity and cross-protection. The H5N1 vaccine was shown to be generally well tolerated and the most commonly reported side effects were headache, arthralgia (joint pain), myalgia (muscle pain), reactions at the site of the injection (pain and redness), fever and fatigue (tiredness).

Initial information collected on the tolerability and effectiveness of the vaccine using the H1N1 antigen were also submitted to the CHMP for evaluation. These included recently announced results from the first clinical trial assessing use of the pandemic (H1N1) adjuvanted vaccine, which demonstrated, that after one dose, the vaccine can provide a strong immune response which exceeds the immunogenicity criteria as defined by international licensing authorities for a pandemic influenza vaccine. The initial tolerability data after the first dose of the H1N1 vaccine indicate a similar tolerability profile as was seen in H5N1 vaccine clinical trials.

GSK is conducting 16 clinical trials in over 9000 subjects including healthy adults, the elderly and children (including infants) across Europe, Canada and the US to further evaluate its pandemic (H1N1) adjuvanted vaccine.

All the data from this clinical development programme will be submitted to the regulators as soon as they are available and they will also be posted on GSK's Clinical Study Register.

GSK supports the WHO's call for post-marketing surveillance of the 'highest possible quality' to ensure extensive safety evaluation of all pandemic vaccines. When governments commence vaccination programmes, GSK will collect information on the safety of the vaccine while it is being used. In addition, the company will undertake a large 9000 people post-marketing safety and effectiveness study.