Geneva  - Swiss drugmaker Novartis said Tuesday it has started shipping vaccines against the A(H1N1) virus, better known as swine flu, to the United States.

The company began sending doses last week from a production seed strain provided by the World Health Organization. This strain had a low yield, but Novartis said it has switched to a higher yielding one to allow for larger production volumes.

The Basel-based pharmaceutical giant also shipped 27 million doses of its seasonal flu vaccine ahead of schedule, in what it said was anticipation of "demand for earlier vaccination with seasonal influenza vaccine created by the current global A(H1N1) influenza pandemic."

The shipment was its largest ever to the US. (dpa)