Asia to test human bird flu vaccine this year

By Tan Ee Lyn

HONG KONG (Reuters) - An experimental H5N1 bird flu vaccine for humans will be tested in Hong Kong, Singapore, Thailand and Taiwan this year and will involve more than 1,000 people, a coordinator for the project said on Friday.

Developed by a European drugmaker, the vaccine uses an inactivated strain of the H5N1 virus isolated in Vietnam, where the disease has killed 42 people since late 2003.

"This is a multinational Phase 3 clinical trial and it aims to recruit over 1,000 subjects," Daniel Chu, principal investigator for the project in Hong Kong, told Reuters.

Phases 1 and 2 were done in Europe, where the vaccine passed safety tests, but Chu declined to identify the drugmaker.

"The key in this vaccine is adjuvant, which reduces the dose of the vaccine," said Chu, who is a medical doctor.

Adjuvants are additives that enhance the effect of drugs or vaccines. Dosage is important because if a small amount of vaccine is effective, it will allow more people to be vaccinated.

The clinical trial will probably kick off at different times in the four places, depending on when government approvals are obtained. In Hong Kong, it is scheduled to start in April and will involve 360 healthy adult volunteers, Chu said.

ONE OF A SMALL NUMBER

The vaccine is one of a small but growing number of inoculations being developed to fight the H5N1 virus, which experts fear could trigger a pandemic killing millions if it learns to transmit efficiently among humans.

The vaccine, to be produced using egg cultures, will require three shots, with the second to be administered on the 21st day and the third, six months after the first shot.

Volunteers aged between 18 and 60 will undergo a number of blood tests afterwards to assess their level of antibodies. Results of the trial are expected around mid-2008.

Since making its first known jump to humans in 1997 in Hong Kong where it killed six people, H5N1 has penetrated many countries in Asia and made inroads into parts of Africa, Europe and the Middle East, killing 169 people since late 2003.

There are now at least four major strains of the virus, some of which are being used by pharmaceutical companies to design what are called "pre-pandemic," or experimental vaccines.

A vaccine designed using a current H5N1 strain might not offer protection against other strains and might even be useless against the eventual pandemic strain because viruses mutate all the time.

Still, experts say the process of making vaccines will lay down the necessary infrastructure so that the time used to make an eventual pandemic vaccine -- anywhere between 4 to 6 months after a pandemic begins -- can be shortened.