SARS: what it is, symptoms, how it spread and whether it still exists

Severe acute respiratory syndrome, or SARS, is a viral respiratory disease caused by a coronavirus. According to NHS 111 Wales, which adapts content originally supplied by the NHS website, there have been two self-limiting outbreaks, both between 2002 and 2004. They resulted in a highly contagious and potentially life-threatening form of pneumonia.

The World Health Organization (WHO) describes SARS-CoV-1 as a respiratory virus that can spread through the air through small infectious respiratory particles. It calls SARS the first severe and readily transmissible new disease to emerge in the 21st century, and notes that it spread to other countries through international air travel.

NHS 111 Wales says SARS originated in China in 2002 and that it is thought a coronavirus strain usually found only in small mammals mutated, enabling it to infect humans.

No, although the names are similar. WHO explains that the number 1 was added to SARS-CoV-1 later to distinguish it from the recently emerged SARS-CoV-2. SARS-CoV-2 causes COVID-19. Both are coronaviruses, but they are different viruses causing different illnesses and different outbreaks.

WHO notes that evidence-based guidance published after COVID-19 emerged will largely apply to SARS as well, and that antivirals against SARS-CoV-2 are likely to be effective against SARS-CoV-1. It also says the extent of any cross-protection from COVID-19 vaccines against SARS remains to be studied.

NHS 111 Wales says SARS has flu-like symptoms that usually begin 2 to 7 days after infection. The incubation period can sometimes be up to 10 days. WHO describes the first symptom as generally a high fever (above 38 degrees C), sometimes with chills and rigors, which may be accompanied by headache, malaise and muscle pain.

After these early symptoms the infection affects the lungs and airways. WHO says that after 3 to 7 days a lower respiratory phase begins with a dry, non-productive cough or shortness of breath that may progress to low blood oxygen levels. In 10 to 20% of cases the respiratory illness was severe enough to need intubation and mechanical ventilation.

• A high temperature (fever) and chills.

• Extreme tiredness, headaches and muscle pain.

• Loss of appetite and, in some people, diarrhoea.

• A dry cough and breathing difficulties.

• An increasing lack of oxygen in the blood, which can be fatal in the most severe cases.

Yes. NHS 111 Wales describes SARS as an airborne virus spread in a similar way to colds and flu, in small droplets of saliva coughed or sneezed into the air by an infected person. Someone who breathes in the droplets can become infected.

It can also spread indirectly if an infected person touches surfaces such as door handles with unwashed hands, and the virus may be spread through an infected person's poo, for example if they do not wash their hands properly after using the toilet.

Evidence from the 2002 to 2003 outbreak showed that people living with or caring for someone with a known SARS infection were most at risk. WHO says most people who contracted SARS were previously healthy adults aged 25 to 70 years, with a few suspected cases among children under 15.

The infection quickly spread from China to other Asian countries. NHS 111 Wales says there were also a small number of cases in several other countries, including 4 in the UK, and a significant outbreak in Toronto, Canada. WHO says cases were detected as early as November 2002 and that the outbreak spread to 28 other countries. The pathogen was identified as a coronavirus at the end of February 2003.

The outbreak was brought under control in July 2003, following a policy of isolating people suspected of having the condition and screening all air passengers travelling from affected countries. During the period of infection there were 8,098 reported cases and 774 deaths, about 1 in 10 of those infected. People over 65 were particularly at risk, with over half of those who died in that age group.

In 2004 there was another small outbreak linked to a medical laboratory in China. NHS 111 Wales says it was thought to be the result of direct contact with a sample of the virus rather than animal-to-human or human-to-human transmission.

NHS 111 Wales says there is currently no cure for SARS and that research to find a vaccine is ongoing. A person suspected of having SARS should be admitted to hospital immediately and kept in isolation under close observation.

Treatment is mainly supportive. It may include help with breathing using a ventilator to deliver oxygen, antibiotics to treat bacteria that cause pneumonia, antiviral medicines and high doses of steroids to reduce swelling in the lungs. NHS 111 Wales adds that there is not much scientific evidence these treatments are effective, and that the antiviral ribavirin is known to be ineffective.

WHO says that while no treatment was available when SARS emerged, the emergence of COVID-19 led to rapid development of antivirals and vaccines, and that antivirals against SARS-CoV-2 are likely to be effective against SARS-CoV-1.

NHS 111 Wales advises not travelling to areas of the world where there is an uncontrolled SARS outbreak, and avoiding direct contact with people who have the virus until at least 10 days after their symptoms have gone.

• Wash your hands thoroughly, using an alcohol-based hand detergent where handwashing is not possible.

• Cover your mouth and nose when you sneeze or cough.

• Avoid sharing food, drink and utensils.

• Regularly clean surfaces with disinfectant.

• In some situations gloves, masks and goggles may be appropriate; WHO says personal protective equipment is mandatory for high-risk groups such as health care workers.

Because no cases have been reported since 2004, SARS is not something people in the UK need to worry about day to day. NHS 111 Wales says WHO continues to monitor countries for unusual disease activity and that, if there were another outbreak, it should be possible to limit the spread of infection.

If you develop a fever and breathing problems, particularly after travel to an area with an outbreak of a new infectious disease, seek urgent advice from NHS 111 and tell them about your travel. For any serious chest infection, the NHS pneumonia page says to call 999 or go to A&E if you are struggling to breathe, have pale, blue or blotchy skin, lips or tongue, are coughing up blood, or suddenly feel confused.

A suspected case of a serious infectious disease like SARS would be directed to NHS infectious diseases services and public health teams, with hospital isolation, as described above. Because SARS is not currently circulating, there is no routine test, vaccine or treatment pathway for it that patients need to arrange themselves.