The Food and Drug Administration (FDA) announced yesterday the first approval in the US of a vaccine against H5N1 avian influenza for use with humans.

Commonly known as bird flu, the current deadly strain of the H5N1 avian virus is not spreading from human to human but only from birds to humans, as well as among birds themselves.

But should H5N1 mutate into a human to human version, this vaccine may give limited early protection until a more effective version can be developed that is more tailored to a pandemic strain.

Dr Andrew C. von Eschenbach, Commissioner of Food and Drugs, said that the threat of a pandemic is one of the most serious worldwide public health issues and that:

“The approval of this vaccine is an important step forward in our protection against a pandemic.”

The vaccine is made by sanofi pasteur, the vaccines division of the sanofi-aventis group, a global pharmaceutical company.

David Williams, president, chairman and chief executive officer of sanofi pasteur spoke of the company’s leadership as a responsible manufacturer of influenza vaccine and that:

“We will play a key role in helping safeguard human health if an influenza pandemic strikes. We look forward to continuing to work with the US government and others, to prepare for this crisis.”

The approval was based on a clinical trial by the National Institute of Allergy and Infectious Diseases that was completed in 2005.

During this trial the vaccine showed an effective immune response against H5N1 with mild side effects when given as two 90 ug/ml intramuscular injections, one month apart, in 103 healthy adults aged from 18 to 64 years.

The most common side effects found in the tral were: pain at the injection site, headache, general ill feeling and muscle pain.

45 per cent of the patients who received the trial dose developed an immune response likely to be sufficient to reduce their risk of contracting the virus. Although the remaining patients’ immune response was lower, it was still thought to be enough to give them some protection against the severity of the virus and reduce likelihood of hospitalization and death.

Meanwhile more information is being collected on the effect of the vaccine on other age groups.

The vaccine will be manufactured but not sold commercially in the US. It will be bought and stockpiled by the federal government for distribution by public health officials when needed.

H5N1 is one version of the influenza A virus commonly found in birds.

Unlike seasonal flu, which produces mild to serious symptoms in most people, H5N1 infection is far more severe and develops quickly, and commonly leads to pneumonia and multi-organ failure.

The US has seen no reported human cases of H5N1 infection, but nearly 300 people have been infected in other countries since 2003, more than half of whom have died.

At the moment H5N1 is primarily a disease of animals, with occasional transmission to humans, albeit with deadly consequences. But should it develop the ability to transmit from human to human, then people would have very little immunity and the ensuing global pandemic would be catastrophic with millions of deaths predicted.

“The timing and severity of an influenza pandemic is uncertain, but the danger remains very real,” said Dr Jesse L. Goodman, Director of FDA’s Center for Biologics Evaluation and Research.

“We are working closely with other government agencies, global partners and the vaccine industry to facilitate the development, licensure and availability of needed supplies of safe and effective vaccines to protect against the pandemic threat,” added Dr Goodman.

Click here for Questions and Answers on the H5N1 Influenza Virus Vaccine (FDA).

Written by: Catharine Paddock
Writer: Medical News Today