Researchers Worried Over Thailand's Bird Flu Experiments On Humans

by Marwaan Macan-Markar

(IPS) BANGKOK -- By revealing its intent to conduct bird flu vaccine trials on humans, Thailand has joined neighboring Vietnam in a venture that has raised troubling ethical questions here.

"It is a brave step that Thailand has taken in announcing its interest to test a bird flu vaccine candidate," Dr. Somchai Peerapakorn, a public health expert at the local office of the World Health Organization (WHO), told IPS.

Last week, Vietnamese health officials announced they had conducted successful laboratory tests for a bird flu vaccine on monkeys and had plans to conduct vaccine trials on a group of volunteers in the months ahead.

But the announcement for such prospective trials in Thailand has stirred a debate within sections of the government. Deputy Prime Minister Chaturon Chaisang has urged more caution before this Southeast Asian country rushes into conducting the vaccine trials.

Chaturon, who also heads the national effort to combat the lethal bird flu virus, said that many questions needed to be answered about the safety and efficacy of the likely vaccine candidate identified for human trials before preliminary tests get underway.

This concern is to be expected, a public health activist told IPS, since the trials call on healthy volunteers to place their lives at risk in testing a potential vaccine that may prove weak or ineffective against the deadly H5N1 strand of the bird flu virus.

But the Ministry of Public Health, which is spearheading this effort, wants the groundwork to be laid for the bird flu vaccine to be tested on Thai volunteers. "Public Health Minister Sudarat Keyuraphan decided in principle to hold bird flu vaccine trials on humans," the 'Bangkok Post' newspaper reported on Sunday.

"(Public health) Ministry officials had told the WHO several times that the government wanted to get involved in developing a vaccine," the paper added.

Thailand, in fact, has thrown its doors open before to host vaccine trials as part of its commitment towards global health. It had participated in trials to develop vaccines for hepatitis B and hepatitis A.

Currently, it is also working towards conducting the final 'Phase Three' trials for a vaccine against the killer disease HIV/AIDS. Since last year, Thai health officials have been identifying healthy, HIV negative women and men to be among the 16,000 people needed for this trial.

The push by Thailand and Vietnam to explore a potent vaccine against bird flu comes at a time when the lethal virus continues to display its high mortality rate -- over 70 percent of those infected by bird flu have died.

Vietnam, which is the epicenter of the virus, reveals this worrying trend. Fourteen people have died of the 21 patients detected with the H5N1 strain of the virus since an outbreak in late December.

In total, 47 people have died of bird flu in Vietnam, Thailand and Cambodia since the virus began spreading through this region's poultry farms at the beginning of 2003, killing millions of chickens.

All but one of the victims who died of bird flu contracted the virus either by consuming contaminated chicken meat that had not been properly cooked or coming into direct contact with the infected birds. The exception was a Thai national, who was infected by a relative in a case described as a limited form of human-to-human transmission.

What worries public health bodies such as the WHO is the prospect of the virus evolving into a more potent form of flu and being passed between humans. Such a mutation could result in a global pandemic, killing millions of people, the UN health agency has warned.

This grim prediction has evolved from medical reports that the human immune system lacks the capacity to combat a virus that may stem from bird flu.

Yet the likelihood of a potent vaccine emerging to insulate people from the lethal virus is not an immediate prospect, said Dr. Khanchit Limpakarnjanarat, of the international emerging infections program at the U.S. Centers for Disease Control (USCDC).

"A classic vaccine trial has many phases and often takes at least seven years if not rushed," he said in an interview. "So it is too soon to talk of an H5N1 vaccine trial getting underway in Thailand."

These trials, which begin to establish the safety and required dosage per vaccine before moving on to the side effects and then its effectiveness, are conducted over three phases.

The first phase requires 20 to 100 volunteers and lasts for a year-and-a-half, said Khanchit, while the second phase needs up to 500 volunteers and can last up to two years. "Phase three will need between 1,000 to 5,000 volunteers and can last up to three-and-a-half years."

Last year, the WHO revealed that it had identified a "seed virus" to be developed further to become a likely H5N1 vaccine candidate. "At least two companies in the United States have been working on this seed virus to develop them to be ready for clinical trails," said Somchai, of the WHO.

Thailand, according to public health officials, is expected to receive a potential bird flu vaccine being developed in the United States for its intended clinical trials.

"Thailand's response to this potential vaccine is not surprising because there are other countries also keen, given the threat bird flu poses," said Somchai. "But it is not an easy undertaking."