FACTBOX: Who is making the swine flu vaccine?

(Reuters) - Pharmaceutical companies are racing to develop a vaccine against swine flu ahead of a possible spread of the virus in the northern hemisphere autumn and winter.

Officials are worried vaccine supplies will prove tight and sales are expected to provide a windfall for the global drugs industry.

Here are details of some companies' progress in making and supplying the vaccine:

GLAXOSMITHKLINE

Glaxo is testing its pandemic H1N1 swine flu vaccine in humans and expects to start giving the results to government agencies in September.

The world's second largest drugmaker said in August it has won orders for H1N1 swine flu vaccine from a further nine governments, taking the total number of doses ordered to 291 million. With more orders still to come, it could be in line for a flu vaccine windfall of more than $3 billion in the next six months or so, according to industry analysts.

SANOFI-AVENTIS

The world leader in flu shots has received major orders from the United States and France for H1N1 flu vaccines and said in July it was in discussion with more than 30 countries about supplies, though it cautioned 2009 sales might not be that large.

An executive said last month Sanofi is "reasonably" comfortable it would be able to honor its contract to supply H1N1 swine flu vaccines to the United States in October. It has a $250 million deal to provide the United States with the swine flu antigen in bulk. Sanofi would also fill France's order of doses between November and early December, as planned.

NOVARTIS

Basel, Switzerland-based Novartis -- whose vaccine gave a strong response even after one dose in a pilot trial -- expects to have a vaccine ready by the end of September or October. It has secured several orders for H1N1 vaccines, though does not expect to see any benefit in its figures until the fourth quarter.

ASTRAZENECA

Astra's MedImmune unit has an initial $90 million order from the U.S. government and has said there is potential for more orders.

MedImmune's vaccine technology, currently only available in the United States, is different from traditional injectable flu shots in that it is a mist sprayed into the nose, where the flu virus usually enters the body.

SINOVAC

China's Sinovac Biotech is the first company worldwide to complete clinical trials for an H1N1 vaccine, which has received approval from Chinese health authorities. Experts have predicted that two shots will be needed to provide swine flu immunity, but Sinovac said a single dose of its vaccine proved sufficient.

CSL

CSL has been in mass production of H1N1 vaccine for several weeks, has completed a first batch of 2 million shots and is producing 1-1.5 million doses per week until it fills all orders.

The Australian group has won a $180 million contract from the United States for H1N1 flu vaccine and an order for 21 million doses for the Australian government, saying in May it expected to book sales of about $250 million from swine flu vaccines in the year to 2010.

BAXTER

Baxter International has completed its first commercial batches of H1N1 vaccine made using a cell culture process designed to be faster than traditional vaccine production methods that use chicken eggs. It has supply contracts with countries including Britain, Ireland and New Zealand, but not the United States, and said in July it could not take on additional orders.

SOLVAY

Solvay said in late July that production of a cell-based H1N1 vaccine for clinical studies would start in August. The Belgian group missed out in June on a Dutch government contract to supply the Netherlands with an H1N1 flu virus vaccine because it could not supply the product within the required timeframe.

GREEN CROSS

South Korea's Green Cross is expected to benefit from the country's H1N1 preparations as the government has set aside $155 million to secure vaccines. Analysts reckon talks with South Korean authorities will guarantee Green Cross to deliver 50 percent of the vaccine supply, but there are concerns about its production capacity.

HUALAN BIOLOGICAL

A Chinese panel of experts gave a green light to a vaccine from Hualan Biological this week. Shares in the Shanghai-listed company have risen 44 percent in two weeks, hitting a life high.

INOVIO BIOMEDICAL

U.S. group Inovio has said its DNA-based H1N1 flu vaccines provided protection against the swine flu strain in pigs and mice. It said in August it expects to begin manufacturing vaccine supplies for H1N1 clinical studies in a "matter of weeks," even though it does not yet have the U.S. approval to begin human trials for that indication.

NOVAVAX

U.S. biotech company Novavax has a new kind of influenza vaccine that works against the swine flu virus in animals. It would have to get approval from the U.S. Food and Drug Administration before it could test the new vaccine in people and years of testing are likely to be required before such a new formulation could be widely used in humans.

(Compiled by Sam Cage in Zurich; Editing by David Cowell)