US FDA approves four swine flu vaccines

The US Food and Drug Administration (FDA) has approved four vaccines against the swine flu virus. Initial supplies are expected to be available within the next four weeks.

CSL, MedImmune, Novartis and Sanofi Pasteur make the vaccines. The Medimmune H1N1 vaccine is a nasal spray instead of an injection and formulated using live, but weakened, virus strains. A fifth manufacturer - GSK - is also expected to gain approval for its vaccine, which has been through positive clinical trials.

"The H1N1 vaccines approved undergo the same rigorous FDA manufacturing oversight, product quality testing and lot release procedures that apply to seasonal influenza vaccines," said Jesse Goodman, acting chief scientist at the FDA.

Wayne Pisano, president and chief executive of Sanofi Pasteur, said: "Obtaining FDA licensure of this vaccine for A(H1N1) pandemic response is a key milestone that will enable Sanofi Pasteur to provide a licensed vaccine to the US government to support pandemic immunisation efforts."

He added that Sanofi Pasteur provides the only influenza vaccine licensed in the US for children as young as six months of age and older.

The US government has purchased 195 million doses of swine flu vaccine and will make shots against the influenza A(H1N1) virus available free of charge from next month. The large-scale 2009 H1N1 vaccination programme will begin mid-October with small amounts of vaccine becoming available the first week of October.

The FDA said preliminary data from adults participating in multiple clinical studies induced a "robust" immune response in most healthy adults eight to 10 days after a single dose. Clinical studies underway will provide additional information about the optimal dose in children.

As with the seasonal influenza vaccines, the 2009 H1N1 vaccines are being produced in formulations that contain thimerosal, a mercury-containing preservative, and in formulations that do not contain thimerosal.

The FDA says people with severe or life-threatening allergies to chicken eggs, or to any other substance in the vaccine, should not be vaccinated.

In the ongoing clinical studies, the vaccines have been well tolerated. Potential side effects of the H1N1 vaccines are expected to be similar to those of seasonal flu vaccines.

The FDA is working closely with organisations to enhance the capacity for monitoring adverse reactions to the vaccine during and after the 2009 H1N1 vaccination programme.