Learning from SARS

When the World Health Organization (WHO) issued its first-ever Global Alert on March 12, declaring Severe Acute Respiratory Syndrome (SARS) to be “a worldwide health threat,” the international scientific community mobilized overnight. Within weeks, scientists had identified the coronavirus that causes the disease and mapped the virus’ genetic code. Biotech companies jumped at the opportunity to develop diagnostic tests and other weapons for the war against SARS. And some scientists predict that, on the fast track, a vaccine could be completed within three years. But the progress of public health efforts to control the disease have proceeded at a slower, less deliberate pace.

The WHO alert followed reports of 150 suspected cases and several deaths in a one-week period from Hong Kong, Canada, Indonesia, the Philippines, Singapore, Thailand, and Vietnam. Early details were spotty. News coverage described the disease as a “form of pneumonia” or a “super-flu.” Its origin was uncertain, though attention focused briefly on an American businessman who had traveled from Shanghai to Hanoi and later died of the disease in Hong Kong. Terrorism had not been ruled out as an explanation.

In fact, the epidemic had been festering for months in the southern Chinese province of Guangdong, but obtaining reliable information from the Chinese government proved difficult. When the WHO began releasing daily SARS reports, beginning March 17, the statistics for China were simply left blank with a footnote explaining that they were being “updated.” After a week of waiting in Beijing, WHO investigators were finally given permission to enter Guangdong province in early April. But over the following weeks, journalists recounted stories of patients being hidden from investigators and physicians being instructed not to publicize SARS deaths.

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Aided by modern travel, the microbes traversed the globe undetected. On March 5, an elderly woman who had returned home to Toronto after 10 days in Hong Kong died from a chest infection, but not before passing the disease on to her son. By April 23, when the WHO issued a travel advisory for Toronto, 136 cases and 15 deaths had been reported in the province of Ontario. However, because the outbreak could be traced to a single carrier, the Toronto health authorities had a better chance of containing it. They closed infected hospitals and identified contacts of infected individuals, and by May 14, with no new cases in 20 days, Canada was removed from the WHO list of SARS affected areas.

But victory had been declared too soon. Two weeks later, Toronto was back on the WHO watch list with 60 new cases. More than 7,000 people were ordered into 10 days of home quarantine, including an entire suburban Catholic high school. When some kids opted to take their quarantine at local shopping malls, public health officials were quick to remind the public of their authority. Ontario Health Minister Tony Clement warned, “We can chain them to a bed if that’s what it takes.” (Toronto was removed from the list again on July 12.)

Meanwhile, there was much finger-pointing over who was to blame for the resurgence. Biologically, it was traced to a single “silent SARS case,” a 96-year-old patient at North York General Hospital who did not show classic symptoms of the disease and was thought to have died of pneumonia. But some blamed senior medical officials for letting their guard down when the initial outbreak subsided. Hospital workers were told they no longer needed to wear masks and gloves if they were not working with SARS patients. In addition, medical officials assumed that anyone who did not exhibit “classical” symptoms was not a SARS case (a particularly dangerous assumption when dealing with a novel agent).

Some commentators also accused Canadian health officials of practicing their own, more subtle brand of number-fudging. The Ontario Ministry of Health and Long Term Care insisted on using its own medical definition of a “probable” SARS case, which was stricter than the WHO definition because it required evidence that the disease was “progressing” on top of evidence of infection. Only the probable cases go into the official statistical reports, so this maneuver tended to lowball the morbidity count. A cynical observer might believe that this was an intentional strategy designed to stave off another travel ban. Eventually, at the urging of his own public health experts, Clement agreed to use the WHO definition, which had the immediate effect of almost tripling the official number of Canadian cases.

In the United States, public health leaders remain puzzled about why there have been so few cases here (73 cases and no deaths in total). “We still do not have a complete understanding of why, so far at least, we’ve not had it spread into the community,” Centers for Disease Control and Prevention Director Dr. Julie Gerberding admitted recently. But so far, the best explanation is pure luck. U.S. Health and Human Services Secretary Tommy Thompson added to growing public fears when he suggested that the disease might return with greater force in the fall flu season. “I am not confident at all,” he said. “I do not think SARS is going to go away.”

Currently, the risk to individuals in the United States and Canada remains extremely low. Yet there is little specific advice that government officials can offer individuals for protecting themselves. When it came to giving advice to the public, Gerberding simply said: “My advice is to kind of follow the same rules your mother taught you in kindergarten. Keep your hands clean, and cover your mouth with a tissue if you’re coughing and sneezing.”

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According to the most recent reports, a turning point has been reached, and the epidemic appears to be in decline worldwide. As of July 2, the WHO reported a total of 8,442 cases and 812 deaths from SARS since the disease first became known. But there have been fewer new cases appearing in recent weeks. Additionally, the Chinese government has taken a more vigorous and open approach to combating the epidemic, setting up roadblocks and even (against the advice of public health officials worldwide) warning that individuals who violate their quarantine could be sentenced to death.

Why should SARS warrant such global attention? After all, there are far more deadly diseases out there. WHO officials argue that the intense focus on SARS is warranted for now because there is a limited window of opportunity within which to defeat the disease. David Heymann, WHO executive director for communicable diseases, explained, “When we put out the announcement about this new disease, one of our major concerns was that maybe we could stop this disease from becoming endemic.”

Moreover, while the number of deaths has been relatively small so far, that could change dramatically if the disease were to spread freely throughout Asia. Estimates of the death rate for people infected with the SARS virus run from 4 percent to 10 percent. The death rate from the Spanish Flu, which circled the globe and killed 50 million people between 1918 and 1920, was lower, about 3 percent. But what made the Spanish Flu so deadly was not a high mortality rate, but the fact that it was so easily transmitted and infected entire populations. In public health terms, the probability of death for the infected individual is only one part of the equation.

The SARS epidemic has also forced discussion about public health legal authority. When a woman arrived in the United States on a plane from China with a fever and cough, CDC officials at the airport wanted her taken to the hospital for examination. However, when she refused to comply, they were powerless to do anything. Federal law allows for the “apprehension, detention, or conditional release of individuals” for quarantine purposes, but only for diseases that are specified in the federal regulations, including cholera, plague, smallpox, and other ancient scourges. On April 4, President Bush issued an Executive Order adding SARS to the list.

Public health experts warn that the real lesson here is not about SARS, but about our capacity to respond to the next big biological threat. In other words, disease prevention requires more than strengthening our own borders. It requires training experts in epidemiology and surveillance and establishing state-of-the-art laboratories around the globe. If SARS persists in Asia for the long term, it will continue to threaten us. As Barry Bloom, dean of the Harvard School of Public Health, writes in a recent issue of Science, “In a world that is increasingly angry at the United States, the lesson here is that it is time to support a global war on disease.”