Drug maker GlaxoSmithKline PLC hopes to start clinical trials in early April for its vaccine against the deadly H5N1 bird flu strain, a company executive said Thursday.

The London-based company would test the vaccine with two different boosters and the first results should come about three months later, said David Stout, president of the company's pharmaceutical operations.

Production is slated to start by year's end, he said on the sidelines of the World Economic Forum's annual meeting.

GlaxoSmithKline has submitted a mock-up dossier to the European Agency for the Evaluation of Medicinal Products, or EMEA, seeking an outline approval to market a vaccine against pandemic flu.

The mock-up process requires companies to conduct clinical trials for safety and to establish the dosage and schedule for core compounds to obtain quick authorization for pandemic vaccines.

The company submitted an adjuvant tested in the mock-up file the company has submitted to the European regulator, Stout said.

An adjuvant stimulates a person's immune response to an infection to help make a vaccine work.

"We know one adjuvant works, and we have a second adjuvant," Stout said. "We believe, based on studies we have done, it will work even better."

"We are going to take both formulations in the clinic in early April, so that we will know we'll be able to pick between the two, and should be able to start production by the end of the year," Stout added.

The company is starting production of its traditional flu vaccine in the next couple of weeks for the next influenza season, Stout said.

"If a pandemic breaks out, we would be able to stop production of the traditional flu vaccine and start production of the pandemic vaccine," he said. "We could start production on a risk basis (without regulatory approval) if that was necessary."