The bird (or avian) flu is a respiratory infection caused by the H5N1 virus. The virus is common among wild birds and usually does not cause any symptoms. But, it can be deadly in domesticated poultry, like chicken and turkeys.

While the virus rarely infects people, in 1997, there was an H5N1 outbreak in Hong Kong—18 people became ill and six died. Since then, the bird flu has infected people in over 15 countries in Asia, Europe, the Near East, the Pacific, and Africa. According to the World Health Organization (WHO), 562 confirmed cases and 329 deaths occurred between 2003-2011. People at the greatest risk are those who have direct contact with sick or dead birds or with surfaces contaminated by the virus. There have been a few cases, though, where the virus spread between people.

Health officials and researchers are concerned that the virus could reach new areas, especially with H5N1 infecting migratory birds. An even greater threat is that the virus could mutate into a more contagious form, with the ability to spread more easily from birds to people and between people.

Antibodies are the body’s natural defense against infection. Vaccines work by triggering the body to make specific antibodies to a particular virus. If a person who has been vaccinated becomes infected with the virus, the antibodies quickly destroy it.

Research studies in humans began in 2005 to evaluate vaccines to prevent avian flu. In 2007, the US Food and Drug Administration (FDA) approved the first US vaccine to protect against a strain of the virus. The vaccine is intended for people aged 18-64 who have an increased risk of exposure to H5N1. Adults receive a series of two shots that are given one month apart. The vaccine, though, is not available to the general public. The US government purchased it for the Strategic National Stockpile, where large supplies of medicines are stored in case of a national emergency.

While researchers work toward protecting the population from H5N1, there are steps you can take to reduce your risk of becoming sick. For example, avoiding direct and indirect contact with wild and domestic birds and making sure all poultry foods are thoroughly cooked are just two ways you can lower your chance of contracting the virus.

In addition, medicines used to treat and prevent the seasonal flu may be effective against avian flu. Oseltamivir (Tamiflu) is currently recommended for the treatment and prevention of H5N1, but there have been some cases where the virus was resistant to this medicine.