Sanofi Pasteur's new H5N1 vaccine shows promise

Sanofi pasteur, the vaccines division of sanofi-aventis Group, has announced data showing that its new investigational H5N1 pandemic influenza vaccine containing a proprietary adjuvant achieved a high immune response at the lowest dose of H5N1 antigen reported to date.

The vaccine containing only 1.9 micrograms of antigen generated a high level of seroprotective immune response in over 70 percent of the participants in a clinical trial and, in the same clinical trial, vaccine containing 3.75 micrograms of antigen generated a high level of seroprotective immune response in over 80 percent of the participants.

Once fully developed, this vaccine should give sanofi pasteur the potential to provide billions of doses in a pandemic situation and greatly increases its ability to produce vaccines for stockpiling in advance of a pandemic. This would be a significant achievement for public health and a breakthrough in research and development of pre-pandemic and pandemic vaccines that is fully in line with sanofi pasteur's early commitment to bring answers to the global threat posed by pandemic influenza.

Results are based on analysis of a clinical trial conducted in Belgium. The trial involved 266 healthy adults, 18 to 40 years of age. The vaccine tested was produced from inactivated H5N1 virus and contains a new, proprietary adjuvant aimed at stimulating the immune system to increase the response to the vaccine. Trial participants received two doses of each formulation. Four levels of antigen dose were tested, with 1.9 micrograms being the lowest dose.

Preliminary data also show good cross-reactivity to a more recently circulating H5N1 strain. Further assessment of the ability of this vaccine to provide cross-protection to variants of the H5N1 strains is ongoing.

Sanofi pasteur has committed, in the event of a pandemic being declared by the World Health Organization (WHO), to producing the largest possible number of doses of its most advanced pandemic influenza vaccine in the shortest possible time. In order to increase its capacity, sanofi pasteur initiated clinical trials with a novel adjuvant aimed at dramatically reducing the amount of antigen needed to elicit a protective immune response to the H5N1 strain currently identified by global health authorities and experts as a potential source for the next pandemic.

According to the WHO, the next influenza pandemic could result in 1 million to 2.3 million hospitalizations and 280,000 to 650,000 deaths in industrialized nations alone. Its impact is expected to be even more devastating in developing countries.

With production of 170 million doses of influenza vaccine in 2006, sanofi pasteur confirmed its leadership as the world's largest manufacturer of seasonal influenza vaccine, supplying a large portion of the estimated global production of about 350 million doses. Sanofi pasteur's Vaxigrip and Fluzone influenza virus vaccines are licensed in over 100 countries.

Influenza is a disease caused by a highly infectious virus that spreads easily from person to person, primarily when an infected individual coughs or sneezes. An influenza pandemic is a global epidemic of an especially virulent virus, newly infectious for humans, and for which there is no preexisting immunity. This is why pandemic strains have such potential to cause severe morbidity and mortality. In an attempt to minimize the impact of a pandemic, many countries are developing national and transnational plans against a possible influenza pandemic situation.