Switzerland has ordered enough bird flu vaccine to protect its entire population in the event of a pandemic, the government announced on Wednesday.

The government said this amounted to 8 million doses of a new pre-pandemic vaccine made by Anglo-American firm GlaxoSmithKline. The cost is expected to be 180 million Swiss francs (about 142 million U.S. dollars).

Supply and stockpiling of the medication is expected to take place from January 2007, said a government statement.

"If needed, it will therefore be possible to offer a first immunization to the whole of the (7.4 million) population," the statement said.

"This vaccination will be voluntary and will only be administered once its effect against a pandemic virus has been proven," it added.

Advanced development efforts to create an effective H5N1 influenza vaccine are currently based on a H5N1 virus isolated from a Vietnamese patient infected by a chicken in 2004.

Since there is no pandemic among humans, this vaccine is referred to as a pre-pandemic H5N1 vaccine. The pre-pandemic vaccine helps prepare the human immune system against the threat of a human pandemic.

Should a pandemic virus emerge that can be easily transmitted among humans, a vaccine based on that specific strain will have to be developed.

The Swiss government has therefore concluded a further agreement with Glaxo for 7.5 million doses of a pandemic vaccine should the need arise.

The immunization program, part of Switzerland's national bird flu plan, will be carried out by the authorities concerned and the cantons.

Switzerland's bird flu action plan, finalized in August, proposes detailed guidelines, plans and responses in the event of an outbreak of the virus in the country.

The central-European country has already built up a stock of the anti-viral drug Tamiflu to treat more than 2 million people and protect health workers.

It has also continued to protect its borders from a possible outbreak of the virus. The latest measures include locking up poultry kept within one kilometer of major Swiss lakes and rivers.

According to the latest Swiss government plan, 1.85 million people in the country could become infected with bird flu if the virus is able to pass from human to human.

In that event, 46,000 Swiss people would be admitted to hospital and around 7,400 people would die. Such a pandemic would cost an estimated 2.3 billion Swiss francs (about 1.8 billion U.S. dollars).