The US has made steps towards achieving its goal of stockpiling vaccines against an avian flu pandemic by granting the first human vaccine licence to Sanofi Pasteur, the vaccines business of Sanofi-Aventis.

H5N1 avian influenza vaccine, which will not be sold commercially, provoked an immune response in 45% of patients who received the highest dose, and was associated with mild side effects. The company has stated that it is working on making the H5N1 vaccine more potent.

Sanofi Pasteur’s vaccine would be used if the current H5N1 avian virus were to develop the capability to spread from human to human, resulting in the rapid spread of the disease across the globe, the US Food and Drug Administration said in a statement on its website. In the event of a pandemic, the vaccine “may provide early limited protection in the months before a vaccine tailored to the pandemic strain of the virus could be developed and produced,” it added.

H5N1 virus, unlike seasonal influenza where infection ranges from mild-to-serious symptoms, is much more severe, usually spreading very quickly and resulting in pneumonia and multi-organ failure.

While there have been no reported human cases of H5N1 infection in the USA, almost 300 people worldwide have been infected with this virus since 2003, and more than half have died.

A very real threat

"The threat of an influenza pandemic is, at present, one of the most significant public health issues our nation and world faces," commented Dr Andrew von Eschenbach, FDA commissioner. "The approval of this vaccine is an important step forward in our protection against a pandemic."

The US government has already purchased 13 million doses of the vaccine for stockpiling, which will be sufficient to administer to 6.5 million people, according to the US Department of Health and Human Services. In theory, it can be delivered to any state in the USA within 12 hours.