SARS: The First Pandemic of the 21st Century

Until the end of 2002, when scores of people in China began falling ill with a mysterious respiratory infection, SARS-CoV was a completely unknown virus. It had almost certainly, however, been hiding in plain sight in the wild for hundreds–if not thousands–of years. But scientists had yet to identify or study it conclusively.

That all changed quickly when the SARS pandemic began that year. Within months, SARS had spread to nearly every continent. Before it was contained, 8,000 people had contracted SARS; more than 700 people died. All told, SARS is estimated to have cost between $30 and $50 billion to the global economy from 2002 to 2003.

Anyone who remembers that pandemic–the first of the 21st century–surely remembers the frightening rhetoric of the time. And yet, there have been no outbreaks of SARS since 2003, so what gives?

EcoHealth Alliance began working in China in the immediate aftermath of the SARS pandemic. Our scientists were part of a team which identified the origin of spillover as a market where live animals were sold in China’s Guangdong Province. Our scientists also identified horseshoe bats as the virus’ natural reservoir. In the years following, China has made some positive changes which could explain why we’ve only seen the one major outbreak of SARS. In fact, it is far less common to see bats for sale now at urban markets than it was in the years leading up to SARS’ spillover.

Of note too is the likely reason SARS spread so far so quickly because it was a new virus that we hadn’t previously known about. Emerging diseases pose a major threat to our health because they are just that: emerging. An outbreak wherein the medical community doesn’t know how the pathogen is spread, what its symptoms are, or the most effective treatment is exceedingly difficult to treat and stop. The impact is all the worst when that outbreak occurs in southern China, one of the world’s most populous regions and a major international travel hub.

What makes SARS of particular threat is that, along with its close relative Middle East respiratory syndrome (MERS), it is the only pathogen on the World Health Organization’s R&D Blueprint list of priority diseases which can be spread from human to human respiratorily. Viruses in other families like filoviruses (wherein Ebola is classified) have higher mortality rates, but are also less easily passed from person to person.

SARS is one of six coronaviruses known to infect humans. Another is MERS. Two more, human coronaviruses 229E and OC43, are responsible for the majority of cases of the common cold. Of the six, four were only identified in the last 15 years.


The study of coronaviruses really only became a priority following the first SARS outbreak. It is likely thanks to the scientific community’s continued studying of SARS-CoV and associated coronaviruses that the world has not seen another.

The fact is, SARS’ emergence onto and relatively quick disappearance from the general public’s consciousness is not evidence that’s it’s of little threat to us. Rather, it’s a testament to the importance of studying viruses outside times of outbreak. At any given time, thousands of viral threats lay in wait; there is no greater threat to our health. We simply cannot just wait for the next one to strike to care and that is why it matters that EcoHealth Alliance stands between you and the next pandemic.