New vaccine being tested offers protection against most avian flu strains

(Nov 22) SINGAPORE : A new vaccine that promises protection against a wide range of avian influenza virus has been developed.

The vaccine which is produced using a cell-based technology is still in its early phase of clinical trials.

The bird flu virus has been detected in many countries - mostly in Asia such as Indonesia, Vietnam and Thailand with different strains reported.

Now preliminary findings of clinical trials of the vaccine developed by pharmaceutical company Baxter show that it can induce antibodies that neutralise widely divergent strains of the H5N1 virus.

Dr Noel Barret, Vice President - Global R&D Vaccines, Baxter AG, said: "It reacts not only with the strains from which the vaccine is made but it also reacts with highly divergent H5N1 strains so the expectations is that such a vaccine could protect against strains which will be emerging in maybe 6 months', 12 months' time and 2 years' time."

The vaccine was produced using a cell-based technology which takes about 11 weeks to produce.

Today most influenza vaccine is produced using the egg-based method where the virus is introduced into the embryos and takes up to 28 weeks to produce.

This method has been used for nearly 50 years.

Baxter says some benefits using the cell-based system for the production of influenza vaccines include doing away with constraints of depending on the supply of eggs which can pose a challenge if a pandemic affects the supply of chickens.

Dr Barret says that the vaccine seems to work well even at the lowest dose level.

The company's study on mice found that 100 percent of mice immunised with the vaccine survived the Vietnam strain, the Hong Kong strain and the Indonesian strain of the H5N1.

The trial on humans shows that more than 75 percent of those injected with the vaccine were able to produce the antibodies.

Dr Barret said: "You cannot talk about efficacy because efficacy means protection against infection. We can't measure that in with H5N1 to date. What we can do is that we can determine the amount of subjects that produce what we anticipate are protective antibodies."

The clinical trial involved 270 healthy adults from Singapore and Austria and was carried out between June and September this year.

Baxter says that Singapore was chosen as a centre for its excellent infrastructure and facilities for conducting research.

Some 115 patients were recruited from Changi General Hospital and the National University Hospital, while the rest were from Austria.

The company says that the side effects from the vaccine are minor, such as fatigue, headaches and a slight fever.

Baxter plans to conduct a larger study involving at least 600 patients.

Among other things, it hopes to determine the optimal dosage in humans for the vaccine to be effective.

There is currently no vaccine against the bird flu on the market. - CNA/ch


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