SARS Lessons Unlearned
Will SARS hit hard again this year or in the future? Experts go over what happened and what may be next.
Unusual Pneumonia continued...
By then, SARS had taken flight -- literally. The worldwide epidemic began when a doctor who had been treating SARS patients flew to Hong Kong and checked in at the Metropol Hotel. In just a few days, he infected at least 17 other hotel guests. They carried the disease to Toronto, Vietnam, and Singapore.
Donald E. Low, MD, chief microbiologist at Mt. Sinai Hospital in Toronto, was in Hong Kong at that time. His hotel was down the street from the Metropol.
"I flew back the next day, and the SARS patient [who carried the disease to Canada] was on the same plane the next day," Low tells WebMD. "In that one day, SARS moved across the globe from Hong Kong to Toronto."
On March 12, 2003, the WHO issued a global SARS alert. Eventually, SARS spread to 26 countries on five continents. More than 8,000 people fell ill. There were 774 confirmed SARS deaths -- about a 10% case-fatality rate.
What ended the SARS epidemic? Klaus StÃ¶hr, PhD, director of the WHO's global SARS laboratory network, credits early identification and isolation of SARS patients. It took heroic efforts from health officials in Hong Kong and elsewhere, who refused to allow anyone with a fever to board any form of transportation. Moreover, air travel to cities with ongoing SARS outbreaks virtually ceased.
"Most countries did temperature screening," StÃ¶hr tells WebMD. "In Hong Kong, every day there were 750,000 people screened at airports, seaports, and land ports. Every day, several hundred people were found to be feverish, and quite a number turned out to be suspected cases of SARS. That is one measure that worked to limit the number of cases. Also helpful was the recommendation to the public to suspend air travel to countries where SARS cases were occurring in the community. These are two measures that we considered successful."
As it turned out, SARS wasn't as easily spread as it first seemed. Most cases could be traced to "superspreaders" -- a few people who became especially ill with especially large doses of especially infectious virus.
"People who were relatively close to the original source of infection obtained a larger dose of SARS virus, were more severely ill, and secreted a large amount of virus," StÃ¶hr says. "With each link in the chain of transmission, the virus excretion rate changed. Those first in the chain were most severely infected. But the super spreading was mostly seen in the initial phase of the outbreak when people did not understand the measures that needed to be taken."