Testing begins on new bird flu spray vaccine

Tests have begun on a new bird flu vaccine that its US developer MedImmune hopes will prove more effective and provide several advantages over current injectable flu vaccines in the event of a bird flu pandemic.

The company is bearing the first fruit of a $170m (€136m) contract recently awarded by the US Health and Human Services Department to expedite the development of its flu vaccine using cell-culture-based production methods.

Delivered as a nasal mist, CAIV-T (cold adapted influenza vaccine, trivalent) is a live virus vaccine that uses a modified attenuated (weakened) form of the flu virus to stimulate a protective immune response in the body and is the next-generation version of MedImmune's currently available nasal flu vaccine, FluMist (influenza virus vaccine live, intranasal).

According to MedImmune, recent Phase III studies have already shown CAIV-T to be effective against seasonal A strains of flu - proving 89 per cent more effective than the flu shot in reducing flu caused by matched H1N1 A strains and 79 per cent more effective than the flu shot against circulating mismatched H3N2 A strains.

MedImmune, together with the US National Institutes of Health (NIH), is now hoping to replicate this success against the potentially-deadly H5N1 avian influenza virus and is now enrolling patients for the first Phase I clinical trials.

"We believe that our influenza vaccine technology may provide several advantages over the flu shot that will be critically important in protecting people against a pandemic influenza virus," said James Young, president of research and development at MedImmune.

"Because of its intranasal delivery, our technology may provide a faster and broader immune response, including providing both systemic and mucosal protection at the site where a flu infection takes hold - which is in the nose."

Additionally, unlike its predecessor, FluMist, CAIV-T does not have to be frozen, making it easier for the medical community to store and administer.

The new bird flu studies will be conducted at the Johns Hopkins Bloomberg School of Public Health Center for Immunization Research, Maryland.

The H5N1 vaccine candidate is being developed under MedImmune's cooperative research and development agreement with the NIH's National Institute of Allergy and Infectious Diseases (NIAID) to produce and test versions of CAIV-T for use against different subtypes of potential pandemic flu strains.

If all goes well, MedImmune expects to have the vaccine on the market within two years and will carry out production from its recently expanded flu vaccine manufacturing facility in Speke, England.