The global public-health network's response to the outbreak of SARS is showing tangible signs of success.
This week the World Health Organization lifted "affected country" status from Vietnam, where the first case of SARS - severe acute respiratory syndrome - was reported in February. The agency also removed a travel advisory covering Toronto, although the city retains its "affected area" status.
While public-health officials are far from declaring victory as the number of cases continues to rise, they say the worldwide effort has already revealed several valuable lessons that could be crucial in containing similar outbreaks in the future - or in coping with a bioterror attack:
• The value of rapid communication among countries and research labs.
• The importance of long-established techniques of quarantine and isolation.
• The use of old-fashioned legwork in tracking down people who may unknowingly carry a virus.
"The need for quarantine and the need for what are historic public-health methods was very great, and I think that's what the world did right," says David Baltimore, a Nobel laureate in medicine and president of the California Institute of Technology in Pasadena. Citing efforts in Vietnam and Singapore in particular, he adds that "in both cases, they seem to have understood very early that they had an emerging infectious disease and they had to treat it by quarantine."
Others cite the speed with which labs worldwide homed in on the virus now deemed responsible for SARS. Researchers took roughly two weeks to identify the virus, and by mid-April labs in Canada and the US had sequenced the organism's genome. With the sequences in hand, researchers are now pressing toward developing accurate tools for diagnosis and eventually vaccines to combat SARS.
"We are very close to a reliable diagnostic test - weeks, not months," according to Julie Gerberding, who heads the Centers for Disease Control and Prevention in Atlanta. Such tests would help clinicians distinguish between actual SARS cases and symptomatic look-alikes, leading to more precise diagnoses and more accurate figures on the spread of the disease.
"The timeline is the fastest I've ever seen," she told the Senate Health, Education, Labor, and Pensions Committee during hearings on Tuesday.
Last week, Health and Human Services secretary Tommy Thompson met with all of the major vaccine manufacturers, according to spokesman Bill Pierce. "The purpose was to send a clear message that this was not business as usual. We're in a hurry, although we're not going to cut corners on efficacy and safety," he says.
As of Wednesday, the WHO reported nearly 5,462 cases of SARS worldwide, leading to 353 deaths. The vast majority of these cases and deaths have occurred in China, which has reported some 400 new "probable" cases in the past week. But even in the US, the much smaller number of cases appears to be rising. Dr. Gerberding told lawmakers that the number of probable cases in the US rose from 41 last week to 52 this week.
With a survival rate of greater than 90 percent for SARS patients, some argue that the outbreak has been overplayed when compared with other public-health threats, such as malaria, which the WHO says kills 3,000 children a day in Africa.
Yet public-health officials point to the outbreak of influenza in 1918, which killed 20 million to 40 million people worldwide, as underscoring the need to quickly apply the public-health version of "shock and awe" tactics to highly communicable diseases
On Capitol Hill, the WHO-led effort also has impressed some lawmakers whose colleagues have taken an increasingly dim view of the United Nation's relevance in handling the crisis with Iraq. "The UN has clearly found a niche where they are doing something well," says Sen. Judd Gregg (R) of New Hampshire.
The effort also has prompted interest in filling gaps in public-health systems at home and abroad. At least 14 states and the District of Columbia have revised quarantine laws in ways that would grant legal immunity to physicians and public-health officials charged with implementing and enforcing quarantines.
In addition, the SARS outbreak could give ammunition to congressional Democrats who have argued that more money earmarked for homeland defense should be spent to bolster local public-health facilities. Analysts note that some clinics in the US still don't have fax machines. The situation is far worse in many developing countries.
In the meantime, SARS is presenting public-health agencies with new puzzles to solve. Researchers in Hong Kong, for example, are trying to find out why young children appear to have a higher survival rate than older teens and adults.
"In this particular epidemic, the word 'constrained' has to be interpreted on a day-to-day basis," Gerberding told Congress. "We are not out of the woods."
• Staff writers Gail Russell Chaddock in Washington and Kim Campbell in Boston contributed to this report.