One year ago, a businessman from southern China probably became the first victim of what eventually became known as SARS. Then in February 2003, a medical professor traveled to Hong Kong where he became sick with an unusual pneumonia. During one night in a hotel he infected at least 12 travelers who returned home to Canada, Vietnam, Singapore and elsewhere. A few weeks later, Carlo Urbani, an Italian physician working for the World Health Organization in Hanoi, determined that what initially appeared to be the flu was, in fact, a new disease. The SARS experience reveals the astonishing power of 21st Century biomedicine and demonstrates how vulnerable the world still is to another devastating plague.
With unprecedented speed, it took scientists just a few months to go from the recognition of SARS as a distinct new disease to identifying the virus that was causing SARS, a member of the corona virus family, known to cause the common cold in humans and various illnesses in pigs, chickens, cats and dogs. By May, scientists had sequenced its genome and by comparing it with viruses founded in animals in southern Chinese food markets, surmised that the SARS virus emerged by species "jumping" from animals to human food handlers.
Scientists have already developed the first generation of testing kits for SARS, a much-need first step in controlling future outbreaks. Unfortunately, these tests are just 60 percent accurate--not reliable enough for routine care. But experts believe that an effective SARS vaccine is two to four years away.
Doctors also made remarkable clinical progress. They determined that SARS was spread by direct bodily contact or on large water droplets in the air, and that it was most easily and effectively spread from severely ill patients. They also determined that quarantining infected people and good infection control, such as careful washing of hands, as well as the wearing of masks for people like health-care workers who are in close contact with SARS patients, could prevent the spread of the virus. To put this progress in perspective, it is helpful to recall that it took about four years to identify HIV as the cause of AIDS and several more years to delineate and implement the infection control procedures preventing its spread. Two decades after identifying HIV, there still is no effective vaccine.
For all these accomplishments, SARS was a wake-up call about the possibility of another deadly worldwide pandemic. For decades, public health officials have worried about a repeat of the Great Influenza Pandemic of 1918-1919, which killed 20 million to 40 million people. In the United States alone, some 675,000 people died, more than all the American soldiers killed in wars during the 20th Century. Several things were remarkable about the 1918-1919 pandemic. It had an incredibly high death rate and, even more worrisome, it killed rapidly. People who were healthy one day were dead the next. And most concerning of all, its victims were not only the elderly and immune compromised, but the young and otherwise healthy.
Initially, concerns about SARS intensified when it was realized that the virus was potentially much more deadly than the 1918-19 flu virus. Approximately 11 percent of all known SARS patients died, and among the elderly the figure was 50 percent. Fortunately, SARS turned out to be a near miss and the epidemic burned out over the summer of 2003. It infected an estimated 8,422 people and left 916 dead in 29 countries. The happy ending of our first meeting with SARS can be attributed to a combination of intense public health control efforts and to the virus' poor ability to spread.
Nevertheless, the SARS epidemic taught us at least four key lessons.
First, SARS emphasized that the real pandemic threat is likely to be a combination of a highly infectious respiratory virus and the global transport infrastructure. Because respiratory viruses are spread by breathing, coughing and touching, they can infect hundreds and thousands of people much more easily and rapidly than viruses spread by sex or contact with bl