U.N. experts approved limited animal vaccinations Thursday in Asia's bird flu crisis to avoid a mass slaughter of livestock in the affected countries.
After a two-day conference, experts said the cautious use of vaccinations could create buffer zones around already infected areas to keep the disease from spreading further.
"The mass culling of flocks outside of infected sites in reaction to outbreaks might therefore be largely avoided and major damage to the livelihoods of rural households and national economies averted," said a joint statement by the U.N. Food and Agriculture Organization (search), the World Health Organization (search) and the World Organization for Animal Health (search).
Hard-hit Vietnam, meanwhile, ordered a nationwide a ban on sales of all live chickens and poultry products, and a top Chinese official said his country's size and still-developing disease reporting systems have made it "weak and vulnerable" to bird flu.
The avian influenza sweeping Asia has killed 16 people — 11 in Vietnam — and jittery governments have slaughtered some 50 million chickens and other fowl to stop the disease from spreading. Indonesia added its name to the list on Thursday, saying it would destroy 10 million birds.
Experts stressed that killing the poultry remains the recommended response to deal with already-infected birds. The extent of slaughter required would depend on local conditions, such as the strength of winds that carry the disease, and the concentration of infected animals, said Bernard Vallat, director-general the animal health agency.
The organizations did not specify how far a buffer zone should be from an infected site.
If done properly, vaccination would be cheaper than providing compensation to restock slaughtered flocks, the experts said.
In previous outbreaks some countries have killed all poultry within three miles of an infected farm, while others have slaughtered only within two miles and used the vaccine for a 1.2-mile ring outside the zone.
In other instances, such as the 1997 bird flu outbreak in Hong Kong, governments have ordered the killing of the entire poultry population, infected or not.
Bui Quang Anh, head of the veterinary department in Vietnam's Ministry of Agriculture and Rural Development, said the country would try to contain the disease without killing its entire poultry stock of 250 million.
"If we do a good job and cull infected poultry and do not allow the disease to spread, we do not need to cull all the poultry," he said. Vietnam Television reported that killing all fowl would cost the country between $700 million and $800 million.
It was not clear whether authorities feared people might catch bird flu by eating infected meat. The WHO says there is no evidence the virus is spreading to people who eat properly cleaned and cooked poultry products. But countries worldwide, including the United States, have imposed import bans on poultry from nations affected with bird flu.
Thailand is the only other country where the virus has jumped to humans, with five deaths.
China has confirmed five outbreaks of the disease and reported 18 suspected ones, but it has not reported any human cases. Chinese officials again rejected rumors circulating in recent days of human cases, saying they were groundless and that there was no attempt at a cover-up.
Chinese officials faced similar accusations last year during the outbreak of severe acute respiratory syndrome, or SARS. Beijing admitted it had the disease after weeks of denial.
"I can say in a responsible way that there is no human (bird flu) infection in China," Vice Health Minister Wang Longde said.
Vice Agriculture Minister Liu Jian vowed stringent measures to stop the virus before it spreads to people. But he acknowledged that "some parts of our animal disease-prevention system are weak and vulnerable, and the public has limited knowledge about the disease and ways to prevent it."
"The poultry population in China is quite big, and production methods are quite diverse. That has brought us some difficulties in controlling this epidemic," he said. "It remains an arduous task for China."
More than 1.2 million chickens, ducks and geese had been slaughtered across China as of Wednesday, according to the Xinhua News Agency.
Liu said China's previously announced plans to destroy all poultry in two-mile radius of an "affected locality" were being carried out, but did not specify whether this applied only to confirmed bird flu cases, or to suspected ones as well.
In addition, all poultry within three miles is being vaccinated, and live poultry markets within six miles are being shut down, Liu said.
Thailand reported two new suspected cases: a 2-year-old boy from northeastern Khon Kaen province and a 67-year-old man from central Chainat province. Thailand has 19 suspected cases in all, nine of whom have died.
Bird flu has now been found in 40 of Thailand's 76 provinces and authorities said nearly 26 million chickens have been killed.
The WHO is working to develop a human vaccine, but an animal vaccine against a closely related strain of the disease already exists. Some farmers have used it to protect against other forms of bird flu and experts believe it could give chickens partial protection from the deadly virus now afflicting farms in 10 Asian nations.
Laos, Japan, Pakistan, South Korea and Taiwan also are battling the disease. Health officials say the strain of bird flu in Taiwan and Pakistan is milder.