Sanofi's human bird flu vaccine tests looking good

Dec 19 2005

French drug company Sanofi Pasteur says early stage trials of an experimental vaccine against H5N1 bird flu have shown it provides a good immune response in humans and is safe.

Sanofi Pasteur, the vaccine unit of drug maker Sanofi-Aventis has called the preliminary results of the Phase I trial on 300 healthy volunteers encouraging.

All around the world governments are struggling to control the spread of the H5N1 bird flu virus and prevent an influenza pandemic from developing.

To date the virus has killed 71 people out of 138 known human cases, all of them in Asia.

It is very significant that Sanofi now says its vaccine has proved effective when given at a lower dose than in an earlier trial, which would allow it available to more people in the event of a pandemic triggered.

Sanofi Pasteur says they found that a 30 microgram dose with an additive that boosts the immune response, in a two-dose regimen, showed an immune response consistent with the requirements of regulators to approve seasonal influenza vaccine.

Earlier tests conducted this year along with U.S. government researchers had used two doses of 90 micrograms each.

The company says it plans to conduct further Phase II trials in 2006 as a good immune response was seen in a significant number of volunteers who tolerated the vaccine well, establishing the basis for further trials and research.

The researchers also say immune responses were seen in a number of volunteers receiving lower doses.

Future trials will examine different dosages that could help low-dose strategies widely discussed by public health experts.

Many experts fear the H5N1 virus could mutate into a form easily transmitted from person to person and sweep the world, killing millions within weeks or months.

So far, almost all human cases can be traced to direct or indirect contact with infected birds.

Sanofi Pasteur will use the latest clinical trial results as part of its "mock up" vaccine dossier to the European Medicines Agency.

The process is expected to reduce the time necessary for approval of a pandemic vaccine once a strain is identified and a pandemic is declared.

The French group is one of several vaccine producers, including GlaxoSmithKline Plc and Chiron Corp, racing to develop a vaccine to protect humans from bird flu.

Although the World Health Organisation (WHO) has welcomed Sanofi Pasteur's announcement, it cautions that an effective vaccine that would be commercially available was still a long way off.

WHO spokeswoman Maria Cheng in Geneva says it is a good first step, but it is preliminary and there is not enough evidence that the vaccine will be effective.

She says as yet it is unknown how well any H5N1 vaccine will match a future pandemic strain, but experts hope it will "prime" a person's immune system so they will get stronger effects from a later, better-matched vaccine.

WestLB analyst Oliver Kaemmerer praises the progress but he too notes that current "pre-pandemic" shots are only a halfway house in developing a truly effective pandemic vaccine, which can only be produced once a new strain of flu that spreads easily from humans to humans emerges.