Back in early July the World Health Organization, or WHO, said the SARS virus had been beaten. No new cases had been reported since the last case on June 15 in Taiwan. So when word came that a young man in Singapore had tested positive for the SARS virus, the news spread like wildfire through the global health community.
SARS, or severe acute respiratory syndrome, is a viral respiratory illness caused by a coronavirus, the type of virus responsible for one-third of all colds. Rumors about a deadly flu came out of China as early as last November, but it wasn't until February 2003 that SARS was first identified. Over the next few months, SARS spread throughout Asia and into more than two dozen countries in North and South America and Europe. The virus infected more than 8,400 people and killed more than 900 before health officials contained it.
Doctors and public health officials say that because most SARS cases occurred after the Northern Hemisphere's cold and flu season, they were easier to catch. However, the virus like many spread through the respiratory route from person to person, may come and go with a distinct seasonal pattern. Thus the medical community is bracing for renewed SARS outbreaks with the onset of the Northern Hemisphere winter in two months.
“We certainly are laboring under the assumption that SARS will return,” says Dr. Anthony Fauci, Director of the National Institute of Allergies and Infectious Diseases at the National Institutes of Health. “ No one in the public health community is complacent in light of a possible reoccurrence. Viruses such as these not infrequently seasonally return. So there's every reason to believe that it will come back. Hopefully, it won't but we need to be prepared for its coming back.”
Dr. Fauci says worldwide awareness of the disease, both its symptoms and how it is spread, should help contain future outbreaks: “One of the reasons the world was caught by surprise and ill prepared was the fact that it had been going on in China for a few months before it got to the point where it was clear that we were dealing with a new disease here. Now all public health measures are perched and geared to be prepared for early cases that could be properly taken care of vis-?-vis isolation and quarantine. I think that kind of alertness and vigilance will hold us in good stead if unfortunately we do get a return of the SARS epidemic.”
Though researchers and health care workers have learned a lot about the SARS virus since February - and there have been major advances in diagnosing SARS - there are still many problems.
A recent health scare in Canada illustrates that point. In early July, a typical "summer cold" virus spread through a nursing home in Vancouver, but in August test results from the Canadian National Microbiology Laboratory indicated the virus might be a mutated form of SARS. Canadian health officials have since determined that the SARS virus did not cause the outbreak, but the conflicting test results illustrate a weakness in the system.
Mark Lipsitc, assistant professor of epidemiology at the Harvard School of Public Health, says diagnostic tests still have a number of drawbacks:
“Those limitations are first of all that the diagnostic tests seem to be not fully specific meaning that they can test positive when in fact the virus is something other than the SARS coronavirus. And that seems to be what happened in the recent outbreak in Vancouver that was caused by a related virus, which nonetheless tested positive on the SARS diagnostics. The other limitation of the diagnostic tests based on antibodies meaning the immune responses of the people who are infected is that those diagnostic tests don't become positive in most patients until several weeks after the infection. And so when a person presents what looks like it might be SARS, those antibody tests aren't very useful at that stage.”
It's tough to make predictions about research and development, say health officials. Both private sector and government funded research studies are ongoing, but until more advanced SARS tests are available, two standard disease control methods may be the best way to fight SARS: quarantine and isolation.
“Ironically, the first new infectious disease epidemic of the 21st century will rely on these century-old methods,” says Art Reingold, director of epidemiology at the School of Public Health at the University of California Berkeley. “I don't think there's any question that if SARS reappears, quarantine and isolation are going to continue to be absolutely at the heart of our public health and clinical prevention measures. In the clinical setting, health care providers are going to have to continue to exercise excellent infection control practices to protect themselves and to protect other patients. So isolation of ill individuals is going to have to be done extremely well, scrupulously. I think the reality is that if SARS does return, what we ultimately of course need is a vaccine, but in the absence of a vaccine we're still largely going to be dependent on centuries-old techniques of isolation and quarantine.”
Unfortunately, because of the nature of viruses, the development of a proven SARS vaccine is years away, says Eleanor Fish, professor of immunology at the University of Toronto: “The microbes that we don't handle well are viruses. There aren't that many effective anti-viral agents. So any new virus infection that appears we haven't yet had an opportunity to develop a vaccine. It's only once the infection has subsided that we then have the opportunity to develop vaccines, to look at other intervention strategies, to come up with ways to deal with viruses.”
There is no SARS vaccine, says Mark Lipsitc at the Harvard School of Public Health, but there is an influenza vaccine. Though it would not prevent SARS, he says it would be a useful tool for the global health community:
“And one of the measures that's been recommended by the WHO recently, and that I think is a very important one, is to use the vaccine for flu as much as possible. Not because it prevents SARS because it doesn't. It prevents flu, but it prevents people from coming in and having what looks like SARS and having to be treated for a SARS-like illness. Therefore, if more people use the flu vaccine and fewer people come in with flu, then that will give the health care system a little bit more room to deal with whatever SARS may actually appear.”
If SARS does reemerge, public health officials say treatment of SARS infected patients isn't very effective and high SARS mortality rates are not likely to drop. For now, they say the best way to contain any future outbreaks will still be quarantine and isolation.