H5N1 (2004)

NIBSC

[BEIJING] The Chinese Ministry of Agriculture announced on Saturday (4 February) that it has granted safety certificates and production licenses for two bird flu vaccines.

The vaccines will be used to immunise birds in China and help curb the spread of bird flu.

Unlike vaccines currently used on fowl in Asia, the new vaccines incorporate segments of the H5N1 virus that has killed 42 people in Asia since January 2004 and caused millions of birds to be culled.

Creating a safe vaccine from H5N1 is a difficult task as the virus has so far killed 75 per cent of those infected.

Chinese researchers from the Harbin Veterinary Research Institute used two different approaches to create their vaccines.

The first vaccine uses a version of H5N1 that has been made inactive by deleting key genes. When injected into a bird, the inactive virus triggers the bird's immune system without causing an infection.

The second is vaccine is composed of a fowl-pox virus that has been modified to contain selected genes from H5N1. The modified fowl-pox virus produces proteins normally produced by H5N1 and these trigger the bird's immune system, again without causing an infection.

Previous vaccines have used less dangerous bird flu viruses. Although these are related to H5N1, vaccines based on them are less effective.

Laboratory tests show that ducks and geese vaccinated with inactivated H5N1 can resist infection from three weeks after vaccination and for up to 10 months. This is four months longer than with previous vaccines.

This vaccine will be given to fowl in the country's main rivers, lakes and wetlands.

Deng Guohua, one of the researchers involved, says the vaccine that combines the fowl-pox virus with H5N1 genes is safe to both poultry and mammals.

The Chinese Ministry of Agriculture says it will be cheaper than previous ones.

Culling large numbers of poultry has been made more of a priority than vaccination in most Asian countries, as some fear that vaccination could lead to a 'silent epidemic' — where the virus would still be present and spread through the population of birds, but without causing any detectable symptoms.

Bird flu vaccines are banned in Thailand, while in China and Indonesia, they are allowed in bird flu epidemic areas (see Bird flu: to vaccinate or not to vaccinate). However, the UN Food and Agricultural Organization revised its guidelines last year in support of vaccination (see UN to support wider use of bird flu vaccine).

To read more about bird flu, visit our site Bird flu: The facts.