Although the death rate from SARS initially appeared to be as low as 4 percent of all people infected, a more detailed analysis of the latest data indicates it probably is much higher -- around 14 to 15 percent -- the WHO said in a written statement.
The fatality rate could reach 50 percent or more in elderly people, but remain close to 0 percent among the young and healthy. "Based on data received by WHO to date, the case fatality ratio is estimated to be less than 1 percent in persons aged 24 years or younger, 6 percent in persons aged 25 to 44 years, 15 percent in persons aged 45 to 64 years, and greater than 50 percent in persons aged 65 years and older," the international health agency said.
To date, SARS has infected 6,903 people and killed 495 in 29 countries. China, Hong Kong and Taiwan continue to struggle with the disease and all have reported new cases and deaths.
China reported 159 new cases and five additional deaths, bringing its total to 4,560 people infected and 219 deaths. Hong Kong increased its total by eight cases and 11 deaths, giving it a total of 1,654 people infected and 204 fatalities. Taiwan, which reported nine cases and one death, now has a total of 125 cases and 11 deaths.
WHO officials said the disease could be contained globally, but officials remain concerned about China's response to the outbreak.
"We believe we can stop (SARS') transmission," Dr. David Heymann, executive director for communicable diseases at WHO, said during a U.S. congressional hearing on the disease.
The major key to containing SARS is China's commitment to deal with its outbreak, Heymann said before the House Subcommittee on Oversight and Investigations. Although the country has the capability to contain the disease, "we don't know if China will commit the full resources necessary," he said.
Meanwhile, U.S. officials, concerned about the importation of SARS cases from travelers, said they were preparing for a much larger outbreak, even though the country has seen relatively few cases thus far, with 63 cases and no deaths.
"It is critical that we be prepared to confront an outbreak of SARS on U.S. soil," Jerome Hauer, acting assistant secretary for public health emergency preparedness at the Department of Health and Human Services, testified during the hearing. "To this end, I recently co-chaired a meeting of the Council of Governments with Mike Byrne of the Department of Homeland Security to bring together health professionals from across the national capital region to aggressively prepare for an outbreak of the SARS virus here," Hauer said.
The Centers for Disease Control and Prevention in Atlanta is purchasing 3,000 ventilators used for isolating SARS patients. They will be added to the nation's emergency stockpile of medical supplies set up to respond to a terrorist attack or other major event involving mass numbers of victims, said Dr. Julie Gerberding, CDC's director.
The new ventilators will be used to supplement the 100,000 ventilators already in the stockpile, Gerberding said.
If the number of U.S. SARS cases increases rapidly, the CDC's first response would be to "act fast," implement quarantines and shut down affected hospitals, she said. The saving grace would be that SARS is "not nearly as infectious as influenza" so it would not spread as rapidly, she added.
However, the disease could take a heavy toll on healthcare workers, as many of the SARS cases around the world have involved physicians and nurses who became infected themselves while taking care of infected patients, she said.
The Food and Drug Administration also has "taken a number of steps to address a possible escalation of SARS cases in the United States," said Dr. Murray Lumpkin, the FDA's principal associate commissioner.
These include putting the necessary regulations in place so experimental medications could be used in an emergency even if the therapies do not yet have full FDA approval, Lumpkin said.
The FDA also is trying to expedite the development of a diagnostic test that can detect whether people are infected with the SARS virus and working with the public and private sector to develop a vaccine and identify potential medications that block the virus.
The agency also has provided an exemption to the approval requirements for CDC so it can get its diagnostic test out more rapidly to labs around the country to help with diagnosing potential SARS patients, Lumpkin said.
The National Institutes of Health in Bethesda, Md., are working to develop a vaccine against SARS, but it probably will take "a couple of years at least," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, a component of the NIH.
It will take until the end of this year at the earliest before researchers will know from experiments in animal models whether a vaccine potentially could work against SARS, Fauci said.
The NIH also is continuing its work in conjunction with officials at the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick, Md., to identify drugs that might be effective against SARS, he said.
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