And not a single country has guidelines on how to distribute limited numbers of ventilators and face masks in case of such a global epidemic, the survey of 45 national plans showed.

The H5N1 avian influenza virus still mostly infects birds, but it continues to infect the occasional person – 256 in total – and has killed 151 people in nine countries.

The World Health Organization considers H5N1 the most likely cause of the next flu pandemic, but stresses that there is no predicting what a flu virus will do. The world has been on alert since 2003, when the virus re-emerged in China and Korea.

"I don't think it is necessarily the case that countries have forgotten about bird flu," said Lori Uscher-Pines of the Johns Hopkins University School of Public Health, who helped conduct the study.

But she said it is difficult to set priorities when a pandemic is so unpredictable. To start a pandemic, H5N1 or any other flu virus would have to first acquire the ability to pass easily from person to person and it is not clear what other changes would occur along with that.

"One of the problems that is inherent in priority-setting now is there a lot of uncertainty about what the strain is going to look like and how infectious it is going to be," Uscher-Pines said in a telephone interview.

The teams at Johns Hopkins and Ben-Gurion University of the Negev in Israel reviewed 45 national pandemic influenza plans from developed and developing countries.

Writing in the online journal Public Library of Science-Medicine, they said the plans would apply to 3.8 billion people, or two-thirds of the world population.

Of the plans, 28 listed individual population groups to receive vaccines in a pandemic and 22 prioritized groups that would get antiviral medications.

Vaccines would be limited

Several companies are working on vaccines against H5N1 and other types of avian flu, but vaccines must match the circulating strain of flu to work well, and a pandemic H5N1 strain has not evolved yet. And flu vaccine production takes months.

Older flu drugs do not work well any more against any kind of influenza but two newer drugs do – Roche AG's and Gilead Sciences' oseltamivir or Tamiflu, and GlaxoSmithKline's and Biota's zanamivir, sold under the brand name Relenza, according to the World Health Organization.

"At current capacity, we cannot expect to vaccinate more than 14 percent of the world's population within a year of a pandemic," the researchers wrote.

"Similarly, although manufacturing capacity has recently quadrupled, it is estimated to take a decade to produce enough of the antiviral medication oseltamivir for 20 percent of the world's population."

This is even with generic drug manufacturers in Bangladesh, Algeria, India, and China producing the drug.

Most countries that do have a plan for distributing drugs and vaccines, including the United States, put health care workers at the top of the list.

Some place children high up, while others target essential service workers, such as communications and telecommunications workers, fire fighters, key government decision makers and power supply workers, the survey found.

Source: Reuters