AFP - A US company said it would make its flu vaccine abroad after a panel of experts Thursday gave the innovative product poor marks and failed to recommend it for approval by the US drug regulator.

"Other countries -- Australia, for example, and Europe -- have already said they feel that our vaccine meets the criteria (for safety), but we have always focussed on the US," Manon Cox, chief operating officer of Protein Sciences, told AFP.

"Now I'm wondering if that's the right strategy," she said after a panel of 11 independent experts failed Protein Sciences' insect-cell-based technology vaccine on safety concerns and said they were not confident it would protect people older than 50 against seasonal flu.

The panel's recommendation -- or not, in this case -- will be passed on to the US Food and Drug Administration (FDA), which is not bound by the experts' opinions but usually follows them, an FDA official told AFP.

Members of the panel said they were not slamming the door on the new vaccine for seasonal flu, which would be the first cell-based flu vaccine available in the United States and could come to market within 75 days of the start of development, but wanted to see more evidence that it was safe.

All the vaccine available in the United States, whether for seasonal or swine flu, currently is made using chicken eggs, while Protein Sciences makes its vaccine by infecting caterpillar cells with a baculovirus carrying the gene for hemagluttinin, a molecule that sticks out of the surface of the flu virus.

A massive campaign to vaccinate millions of Americans against swine flu has been hampered by a severe shortage of vaccine, which has been blamed in part on the slow rate at which the (A)H1N1 virus grows in eggs.

Lawmakers have questioned whether vaccine production has also been held up by the fact that only one of the five companies producing flu vaccine does so in the United States.