President Bush's strategy to prepare for a potential flu pandemic includes $18 million for manufacturing and trials of a human vaccine in Vietnam, a country that has suffered the most human deaths from the bird flu.

Health and Human Services Secretary Michael Leavitt traveled to Southeast Asia in October and met with scientists in Vietnam who are working to develop a vaccine.

Leavitt said he offered U.S. help in setting up trials to test their vaccine for effectiveness.

For the bird flu to become a worldwide threat the virus would have to mutate into a form that spreads easily from person to person. Until such a mutation occurve Vietnam has the capacity to make a vaccine.

Experiments on vaccines are under way in other countries, but Leavitt noted that there is a worldwide shortage of vaccine manufacturing capacity.

In August, Vietnam launched an effort to vaccinate its poultry against the disease, administering the first of about 20 million shots.

More than 40 people in Vietnam have died after contracting the bird flu, primarily from the animals themselves. So far, most human infections have been traced back to contact with birds.