The regulatory authority Swissmedic said it had received data on the vaccine for adults, but not for pregnant women and very little data for children.

"For this reason, Swissmedic has not yet authorised the administration of Pandemrix to pregnant women, children under the age of 18 and adults over 60," the regulator said in a statement.

Pandemrix was one of two vaccines approved by European Medicines Agency (EMEA) in September for usage against the A(H1N1) virus, and GSK said in early October that it had orders for 440 million doses of the vaccine.

While the Swiss regulator did not give the green light for the usage of Pandemrix by vulnerable groups, it said Focetria, a vaccine produced by Swiss pharmaceutical giant Novartis, was safe to be used by both children and adults.

In this instance, Swissmedic said it "based its decision largely on the EMEA authorisation".

"In accordance with this, Focetria is recommended for use in adults and children over six months old," it said.

As for usage by pregnant women, Swissmedic left it to doctors to weigh up the advantages and disadvantages of the vaccination.

The regulator added that it was still examining a second Novartis vaccine, Celtura.

Citing anonymous sources, Swiss daily Tages Anzeiger had reported on Saturday that Celtura had problems gaining regulatory approval here due to possible bacterial contamination.

The vaccine is produced by a technique using cell cultures from dog kidneys, allowing more rapid production than by the more classical method using chicken eggs, according to the company.

However, Tages Anzeiger said Swissmedic had found bacterial contamination in test batches of Celtura.

A spokesman at Swissmedic told AFP then that the agency could "neither confirm nor deny" the report, while Novartis had denied that it was facing problems gaining approval for the vaccine.

Countries in the northern hemisphere are in the midst of rolling out vaccinations programmes, in preparation for the coming winter.

The WHO has recommended that health workers be given the vaccines in priority, followed by vulnerable groups such as pregnant women and young children.

Nearly 5,000 people have died from swine flu infections since the A(H1N1) virus was uncovered in April, according to data issued by the World Health Organisation last week.

(c) 2009 AFP