By Sybille de La Hamaide

PARIS Governments should consider vaccinating birds against bird flu to avoid the virus - which has already killed hundreds of millions of birds and infected mammals worldwide - turning into a new pandemic, the head of the World Animal Health Organisation (WOAH) said.

The severity of the current outbreak of avian influenza, commonly called bird flu, and the economic and personal damage it has caused, has led governments to reconsider vaccinating poultry. However, some, like the United States, remain reluctant mainly because of the trade curbs this would entail.

"We are coming out of a COVID crisis where every country realised the hypothesis of a pandemic was real," WOAH Director General Monique Eloit told Reuters in an interview.

"Since almost every country that does international trade has now been infected, maybe it's time to discuss vaccination, in addition to systematic culling which remains the main tool (to control the disease)," she said.

The WOAH is holding a five-day general session from Sunday, and will be focus on global control of highly pathogenic avian influenza, or HPAI.

A WOAH survey showed only 25% of its member states would accept imports of products from poultry vaccinated against HPAI.

The European Union's 27 member states agreed last year to implement a bird flu vaccine strategy. France is set to be the first one, starting with ducks in the autumn.

"If a bloc like the EU, which is a large exporter, starts moving in that direction, it will have a ricochet impact," Eloit said.

The U.S. department of Agriculture (USDA) told Reuters on Friday that "in the interest of leaving no stone unturned in the fight against HPAI, USDA continues to research vaccine options that can protect poultry from this persistent threat".

However, it still considers biosecurity measures to be the most effective tool for mitigating the virus in commercial flocks, it said in emailed answers.

The risk to humans from bird flu remains low but countries must prepare for any change in the status quo, the World Health Organization has said.

Eloit said vaccination should focus on free-range poultry, mainly ducks, since bird flu is transmitted by infected migrating wild birds. Vaccinating broilers, which account for about 60% of global poultry output, makes less sense, she said.

The H5N1 strain that has been prevalent in the current HPAI outbreak has been detected in a larger number of mammals and killed thousands of them, including sea lions, foxes, otters and cats.

(Reporting by Sybille de La Hamaide; Editing by Hugh Lawson)