AstraZeneca unveiled a significant push into vaccines and advanced “biological” medicines yesterday with the $15.2 billion (£7.6 billion) acquisition of MedImmune, an American biotechnology group.

The deal, which gives Britain’s second-largest pharmaceutical company access to MedImmune’s flu vaccines, an antiviral treatment for babies and about 45 experimental drugs, quickly drew criticism for being expensive.

AstraZeneca, which intends to merge MedImmune with Cambridge Antibody Technology Group (CAT) — another biotechnology company, which it bought last year — paid $58 per share for MedImmune, a 53 per cent premium on its closing price of $37.84 on April 11, the day before the company revealed that it had appointed Goldman Sachs to handle a possible sale.

“We like the strategy and the fit with CAT . . . but you have to grit your teeth in terms of price,” Peter Cartwright, the pharmaceuticals analyst at Evolution Securities in London, said. “The financing costs will be around $1 billion per year, so it will be earnings-dilutive until 2009.”

The acquisition of MedImmune, the world’s seventh-largest biotech group by market value, will help to bolster AstraZeneca’s pipeline of new medicines before a string of patent expiries on some of its key products. MedImmune’s range of marketed products includes FluMist, a flu vaccine delivered by a nasal spray, and Synagis, a treatment for infant respiratory infections. The pair had sales of $1.2 billion last year and are expected to grow at a 12 per cent rate between now and 2010.

The group is also developing drugs for the treatment of cancer, inflammatory and respiratory diseases and has a substantial drug manufacturing operation for biologic — or large molecule — drugs that some consider to represent the future of medicine.

Jon Symonds, AstraZeneca’s chief financial officer, said that the deal would allow for synergies worth $500 million over the next five years.

David Brennan, the chief executive, said: “This acquisition represents a transforma-tional step to deliver our biologics strategy sooner than anticipated.” He denied that AstraZeneca had overpaid for the company and added that “strengthening the pipeline continues to be the highest priority”.

To smooth the transition to a merged company, AstraZeneca said that it would pay many of MedImmune’s near3,000 staff a one-off retention bonus. David Mott, the chief executive, and James Young, the president, will also remain in senior roles.

AstraZeneca, whose sole adviser on the deal was Merrill Lynch, is believed to have fought off stiff competition for MedImmune from rivals including Novartis, of Switzerland, and Merck and Wyeth, of the United States. The auction process began about six weeks ago after an unsolicited approach to MedImmune. The all-cash transaction is expected to close in June. AstraZeneca

Shape of the market worldwide

— Global vaccines market is estimated to be worth $13 billion annually

— About 3 per cent of total global drug market

— Biggest players include GlaxoSmithKline, Sanofi Pasteur, Merck and Novartis

— Sanofi Pasteur, the vaccines business of France’s Sanofi-Aventis, is the world’s largest vaccine maker with annual sales of over €2 billion and over 8,500 employees

— Analysts have predicted that the global vaccines market will double in size to $26 billion by 2011

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