Severe Acute Respiratory Syndrome, also known as SARS, is a new and mysterious disease affecting thousands of people currently worldwide. Although little is currently known about the disease, breakthroughs occur on a daily basis concerning SARS. The disease is caused by a virus that invades the lungs of a human, causing severe pneumonia-like symptoms. Viruses are able to change their DNA, or mutate, and by doing so, are able to become resistant to many of our current vaccines. This is why many different types of SARS viruses were found throughout the world.

Viruses are not classified as living species because they lack the proteins to replicate themselves although they do contain a DNA or RNA genome. They require the DNA replication proteins of a living cell to make more copies of the virus and begin an infection. SARS human coronavirus is transmitted through tiny droplets of saliva of infected people. When a healthy person ingests these droplets, the virus makes its way into the lungs. When in the lungs, it attaches itself to the cells of the alveoli (tiny pouches on the surface of the lungs used for the oxygen-carbon dioxide gas exchange in normal human respiration or breathing). SARS virus then injects its genome into the cell thereby taking over its replication proteins. The cell is held hostage by the replicating virus and many copies of the virus are made. Finally, the cell becomes filled with viruses and it bursts. It releases the newly synthesized viruses to invade other cells and repeat the process. This then leads to a full- blown SARS viral infection. SARS virus is thought to be transmitted through the air (airborne) also.