Severe acute respiratory syndrome, or SARS, was a contagious and potentially fatal respiratory illness. An outbreak occurred from 2002 to 2003, but the disease is no longer circulating.

SARS was the result of infection by a coronavirus that scientists named SARS-associated coronavirus (SARS-CoV). SARS-CoV is related to SARS-CoV-2, the virus that causes COVID-19 infection.

While COVID-19 is currently affecting people around the world, no reports of new cases of SARS have surfaced since 2004.

The respiratory illness known as SARS first appeared in China in November 2002, and scientists identified it in February 2003.

SARS spread to over 24 countries before health authorities managed to contain it. Nevertheless, between November 2002 to July 2003, there were 8,098 cases worldwide and 774 deaths.

In the United States, there were eight laboratory-confirmed cases and no fatalities. All eight people who the illness affected had traveled to areas where SARS was prevalent.

Global cooperation enabled health authorities to deal swiftly with the threat of SARS and to rapidly contain the illness. SARS infections are not occurring now, although they could reappear one day.

a crowd of people in Asia where a lot are wearing face masks to protect themselves from SARSShare on Pinterest
From 2002 to 2003, an outbreak of SARS spread across 24 countries.

The coronavirus SARS-CoV causes SARS. A coronavirus is a common form of virus that typically leads to upper respiratory tract illnesses, including the common cold.

Seven different kinds of coronavirus can infect humans. Four of these are common, and most people will experience at least one of them during their life.

The three other coronaviruses cause:

The three most recent coronaviruses have all emerged since 2002 and are more likely to be life threatening than the previous ones.

Find out how SARS and MERS compare with COVID-19 here.

Experts believe that coronaviruses, such as SARS-CoV, spread through close human contact and in droplets from coughing and sneezing. The viruses may be airborne or travel in ways that scientists do not yet know about.

The body likely absorbs the respiratory droplets through the mucous membranes of the mouth, nose, and eyes.

Ways of transmitting the virus may include:

  • hugging and kissing
  • sharing utensils for eating and drinking
  • speaking to others within a distance of 3 feet
  • touching someone directly

If droplets from one person land on an object such as a door handle or a telephone, someone else can pick up the virus if they touch these items.

In 2015, scientists found evidence that SARS-CoV might survive on a dry surface for extended periods, possibly for several months.

SARS was a zoonotic disease, meaning it was of animal origin but passed on to humans.

The Centers for Disease Control and Prevention (CDC) note that 75% of emerging infectious diseases come from animals, including rabies and Ebola. Most zoonotic diseases originate in wild animals rather than pets or domestic animals.

Some animals can carry a virus without becoming sick because their bodies are accustomed to the virus. This fact means they are likely to have immunity.

Viruses can change, however. If a virus changes through contact with another type of animal, it can become unpredictable and possibly dangerous.

When a new virus first emerges, people do not have immunity. In time, the immune system develops antibodies for the new virus, and these antibodies equip it to fight the resulting disease.

When swine flu (H1N1) first appeared in 2009, for example, there were concerns that a pandemic could develop. Now, it is one of the seasonal flu strains that pharmacists include in the annual flu vaccine. Many people also have immunity to H1N1.

In 2019, a new coronavirus, which scientists identified as SARS-CoV-2, began making people sick in China. This is the virus causing the current COVID-19 pandemic.

When SARS was occurring, its symptoms appeared 2–7 days after a person was exposed to the virus, but they could also take up to 10 days.

The first symptom was a high fever of more than 100.4°F (38.0°C). Other mild respiratory symptoms were similar to those of flu.

Other early symptoms included:

  • aches
  • chills
  • diarrhea in 10–20% of people

These symptoms developed over the course of 7 days.

After 7–10 days, the person might then have noticed:

  • a dry cough
  • shortness of breath
  • low oxygen levels in the body known as hypoxia

Most people with SARS developed pneumonia while some had long-term damage to their liver, kidneys, and lungs.

These complications were more likely in those more than 60 years of age, and most people with SARS made a full recovery.

To diagnose SARS, a doctor would ask the individual about symptoms and carry out a physical examination. They would likely ask whether the person had recently spent time in an area where SARS was present or taken care of a person with SARS.

According to the World Health Organization (WHO), for a diagnosis of SARS, a person must have all the following:

  • a fever of at least 100.4°F (38°C)
  • one or more symptoms of lower respiratory tract illness, such as cough, difficulty breathing, shortness of breath
  • radiographic evidence to suggest pneumonia
  • no alternative diagnosis to explain the illness

When it was occurring, SARS was rare, and the symptoms overlapped with those of the flu and pneumonia.

It would only be possible for a person to have SARS if there was a current outbreak, and they had been to an area where the illness was occurring. At the time of writing, there have been no reports of SARS since 2004.


Laboratory tests can help identify SARS-CoV.

These include:

  • blood tests
  • stool tests
  • tests of nasal secretions
  • imaging tests to detect pneumonia

These tests might not be reliable during the early stages of infection.

SARS is a reportable disease and a medical emergency.

During the 2003 outbreak, people with SARS in the U.S. did not need to enter quarantine. The WHO recommended isolating patients and using barrier techniques to prevent the spread of the virus, including filter masks and goggles.

No drugs, including antibiotics, appeared to be effective against SARS. Instead, healthcare providers offered supportive care, including the use of medications to relieve symptoms, such as fever and a cough. In the hospital, some people needed a ventilator to help them breathe.

As with other infectious diseases, some simple steps would help prevent the spread of SARS-CoV if it were to occur again.

These include:

  • washing hands frequently or cleaning with an alcohol-based detergent
  • avoiding touching the eyes, mouth, and nose with unclean hands
  • covering the mouth and nose with a tissue when coughing or sneezing
  • avoiding sharing food, drinks, and utensils
  • staying at least 3 feet away from other people
  • regularly cleaning surfaces with disinfectant

Similarly, anyone with symptoms of SARS would limit interaction with other people until 10 days after their symptoms improve.

SARS appeared to be contagious only after symptoms emerged, and it was most likely to spread during the second week of illness, according to the CDC.

A SARS outbreak occurred in 2002–2003. It resulted from SARS-CoV, a coronavirus related to the virus responsible for the current COVID-19 pandemic.

When the outbreak occurred, health authorities acted quickly and were able to prevent widespread disease. Since 2004, there have been no recorded cases of SARS anywhere in the world.

There is currently no cure for SARS and no vaccine against SARS-CoV, but scientists have continued to investigate.