LONDON (Reuters) - Vaccines, until recently a sleepy backwater in the global healthcare industry, are now outpacing drugs in terms of sales growth, the world's two largest vaccine makers said on Thursday.

GlaxoSmithKline Plc and Aventis Pasteur, who both claim a 24-percent share of the $6.5 billion-a-year global vaccine market, said demand was being driven by new products, including combination jabs and new adult treatments.

The infant sector currently accounts for two-thirds of vaccine sales but market dynamics are changing, helped by growing demand for flu shots among the elderly and increased use of vaccines by tourists visiting tropical countries.

At the same time, the threat of bioterrorism in the wake of September 11, 2001, has spawned a new business in supplying vaccines against smallpox following fears that the deadly virus might be used as a weapon.

The result has been the birth of a new generation of niche vaccine companies, typified by Britain's PowderJect Pharmaceuticals Plc and Acambis Plc, both of which will make their first profit this year.

Jean Stephenne, vaccines head at GlaxoSmithKline Plc, told an ABN AMRO conference that global vaccine sales would rise by more than a fifth to about $8 billion by 2005, underlying a long-term trend which has seen a tenfold increase in sales since 1980, while drug sales have risen only five times.

Both GSK and Aventis expect to clock up vaccine sales of around $1.6 billion this year.

Adrian Howd, biotechnology analyst at ABN AMRO, said vaccines were now one of the fastest-growing areas of healthcare, with demand for new products outweighing supply, and the total market set to top $10 billion by 2010.

Consolidation within the sector is likely, Howd says. The industry at present is highly fragmented, with more than 60 companies, but firms will seek critical mass to compete effectively.

NEW PHASE

"You're seeing the launch of a new phase in the industry today," said Paul Kirkconnell, corporate vice president of business development of Aventis Pasteur.

He predicted the global vaccine market would double over the next decade after 14 percent compound annual growth in the 1990s. That compares with global drug sales of just eight percent in the year to September, according to healthcare information firm IMS Health. The revival of the vaccine industry, which was once dismissed as a low-margin and commoditized business by many big drugmakers, reflects a series of innovations ranging from new pediatric combinations to novel disease targets.

Among new disease targets, Stephenne said he was particularly excited by experimental vaccines to prevent infection by the human papilloma virus (HPV) that causes cervical cancer.

Both Merck and GSK have HPV vaccines in development that will compete in a market that Stephenne estimated would eventually be worth some $3 billion pounds a year.

Professor George Dougan, director of the Center for Molecular Microbiology and Infection at Imperial College, London, said recent scientific progress had opened many new opportunities.

These include the development of innovative drug delivery mechanisms and the use of new adjuvants, substances that are added to vaccines to enhance their effectiveness.

Ultimately, vaccine developers could move to using DNA to trigger an immune response. Such DNA vaccines, if successful, would be simple to use and store, and might have therapeutic applications in treating patients already suffering from diseases, including cancer. ($1=.6364 Pound)