Shares in US group Baxter International were given a lift on Friday following news that European regulators are supporting the approval of its pandemic H1N1 vaccine Celvapan, with a final decision imminent.

Batches of Baxter’s vaccine have already been shipped to countries around the globe, including the UK and Ireland, and if the final stamp of approval is issued by the European Commission governments will then be able to release the jab for their respective immunisation programmes.

The Committee for Medicinal Products for Human Use’s green light for Celvapan’s full marketing authorisation was based on a ‘mock-up’ file submitted by the firm under a system introduced by the European Medicines Agency in 2004 to allow for fast-track assessments of potential pandemic flu vaccines.

Mock-up files are based on an influenza strain available at the time of testing that could cause theoretically cause a pandemic, so that once a pandemic is declared a vaccine using the actual circulating strain can get accelerated approval, thereby offering the public faster protection.

The mock-up file for Celvapan contains data from five completed clinical trials (using a different strain to H1N1) involving over 1,300 people, and more than 3,500 people have also been vaccinated in an ongoing Phase III study, demonstrating its safety and efficacy, the group noted.

In addition, Baxter is currently conducting two randomised trials in 400 healthy adults age 18 and over and in 400 children and adolescents to further evaluate the safety and immunogenicity of the H1N1-based vaccine, data from which will be submitted to regulators post approval. Furthermore, following the roll out of national immunisation programmes the company plans to conduct a large-scale observational study with Celvapan H1N1, it said.

First non-adjuvant vaccine in EU?
The vaccine is the first cell culture-based and non-adjuvanted vaccine - which means it contains no adjuvants to boost the immune response to the jab - to receive a positive opinion in the European Union, and early safety data indicate that Celvapan H1N1 is well-tolerated as “observed systemic and local reactions are similar to those generally experienced after vaccination with licensed seasonal influenza vaccines”, according to Baxter.

Governments around the globe are currently preparing for an expected second-wave of H1N1 infections during the traditional Autumn/Winter flu season. Last week, the European Commission approved GlaxoSmithKline’s H1N1 pandemic vaccine Pandemrix and the CHMP issued a positive opinion for Focetria, for which a full nod is also expected shortly, adding to the growing arsenal against the virus.