"I think there is a real possibility that we will have a pandemic of flu due to one of these bird flu viruses. There are a lot of things we don't know about the epidemiology of flu and how flu pandemics get started. I think it is definitely something that we need to take seriously and worry about and be prepared for, but I don't know that it is inevitable."
Dr. Alex Thiermann, special adviser to the director general of the World Organisation for Animal Health (OIE)
"The H5N1 virus has resulted in the killing of 150 million chickens, and it has only infected 169 people. We need to remind everybody that we're dealing with a poultry disease, and we need to deal with it in the poultry. And of course it has a pandemic potential, but we have very good measures to prevent it by acting in poultry. Our concerns are in the countries that have very weak veterinary infrastructure, and don't have the resources or technical personnel to fight it."
Professor Sir David King, chief scientific adviser to the British government and head of the Office of Science and Technology
"It is very important to keep things in proportion, and to make a distinction between the virus in birds and the virus in humans."
"Your chances of winning the lottery are about one in 14 million. Your chances of catching bird flu are more like one in 100 million, even if we had H5N1 among the chicken population in Britain."
Dr. David Fedson, retired medical director of Sanofi-Aventis, the world's third largest pharmaceutical company that's working on developing a human bird flu vaccine
"It's really impossible to say how close we are to the next pandemic. Everyone who is knowledgeable about this will say the pandemic is inevitable. We know the pandemic clock is ticking. We just don't know what time it is. As each day, week, month goes by we are getting closer to the inevitable next pandemic."
Dr. Martin Blaser, president-elect of the Infectious Disease Society of America
"Although the world needs to be prepared for a flu pandemic in the future, it's important to keep in mind that there is no pandemic right now. Even the H5N1 virus that is currently circulating in Asia and Europe primarily causes a disease affecting birds. There have been very few cases of bird-to-human transmission."
Dr. Andrew Pavia, chairman of the Infectious Disease Society of America's Pandemic Influenza Task Force
"Most bird flus emerge briefly and are relatively localized. The most worrisome thing about H5N1 is that it has not gone away."
"We should be worried but not panicked."
Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention
"Even if it does enter through a migratory bird at some point, which won't be surprising, we have a wonderful system of surveillance and a Department of Agriculture and a Department of the Interior here that know what to do and have been handling bird viruses for many, many decades."