Skip to content

Coronavirus v SARS: How similar are the outbreaks?

A woman wearing a face mask in Beijing, China
Why you can trust Sky News

By Emily Mee, news reporter, and Carmen Aguilar-Garcia, data journalist

With cases of a new coronavirus rising and concern growing over the spread, comparisons are being drawn the deadly SARS outbreak in 2001.

Both are strains of coronavirus, and virologists say the current strain, 2019-nCoV, is a close relative to SARS.

But how similar are the two diseases, and what can we expect to happen?

Where did they originate?

Both illnesses originated in China and are believed to have been first transmitted in wet markets.

More on Coronavirus

Coronaviruses are zoonotic diseases, which means they can jump from animals to humans - especially in locations where humans and animals are in close proximity.

Chinese scientists believe the new coronavirus, dubbed the Wuhan virus, could have been transmitted by bats at the seafood market in the city of Wuhan.

SARS is thought to have been transmitted from one species of animal - potentially bats - to civet cats, which then infected humans at a market in the Guangdong province of southern China.

The resident wear masks to buy vegetables in the market on January 23, 2020 in Wuhan, Hubei¬China
Image: Residents wear masks to buy vegetables in the Wuhan market
A member of the Thai Airways crew disinfects the cabin of an aircraft
Image: A member of the Thai Airways crew disinfects the cabin of an aircraft

How many people have been infected?

The number of cases of the Wuhan virus could be far higher than reported, as those with milder or no symptoms may not have been tested for coronavirus.

Some researchers have suggested the real figure is 100,000 cases or more.



There have been no confirmed cases of SARS since 2004.

Both diseases have been concentrated in China, although managed to spread after people travelled from China to other countries.

How do the viruses spread?

The magnitude of an outbreak depends on how easily the virus can spread.

Although research is still at early stages, some studies estimate each individual with the Wuhan virus could infect on average 2.6 (between 1.5 and 3.5) people.

This makes it as contagious as SARS.

How fast a virus spreads can also be affected by its incubation period - the time between being exposed to the virus and the onset of symptoms.

As the Wuhan virus has a longer incubation period than SARS, and it can be passed on before a person experiences symptoms, it is harder to contain.

SARS patients were largely isolated as soon as they became contagious, when symptoms began to show, and therefore it was easier to trace others they may have come into contact with.

Wuhan virus vs SARS
Image: Wuhan virus vs SARS

How deadly are they?

Deaths from the Wuhan virus have been concentrated in mainland China, with only one confirmed case outside China - in the Philippines.

The death toll from the new coronavirus in mainland China has exceeded the deaths from the 2002-2003 SARS outbreak, which killed 349 people in mainland China and 299 in Hong Kong.

However, 16% of deaths from SARS occurred outside China and its administrative regions.

With the possibility that the number of cases is actually far higher than recorded and a rise in the number of recoveries, the fatality rate of the Wuhan virus could be much lower than currently reported.

In the 20 days since cases of the Wuhan virus started being recorded, the World Health Organisation (WHO) declared 530 of those infected had recovered.

In comparison, 1,706 people had recovered from SARS after 95 days during the 2003 outbreak.

Who were the victims?

Most of those killed by the Wuhan virus were over 60 and many had pre-existing health conditions, but at least five victims under the age of 60 have been recorded.

Similarly, SARS deaths were largely recorded in older patients and those with underlying health conditions.

Please use Chrome browser for a more accessible video player

Fear and anger grows over the coronavirus in Hong Kong

According to a WHO report from May 2003, less than 1% of those killed were under the age of 24, and up to 6% of 25 to 44-year-olds who were infected died.

Can the viruses mutate?

Both the Wuhan virus and SARS are believed to be mutations of a strain of coronavirus found in small mammals.

Some researchers fear the new coronavirus could mutate again so that it spreads more efficiently or becomes more harmful.

Worshippers wear masks at Che Kung Temple in Hong Kong
Image: Worshippers wear masks at Che Kung Temple in Hong Kong

However, mutations do not necessarily make a virus more virulent.

A 2018 study of SARS in primate cells found a mutation of the 2003 outbreak is likely to have made the virus less harmful.

What was China's response like?

Chinese authorities were heavily criticised for their response to the SARS outbreak after they attempted to cover it up.

Patients were kept in hotels and driven around in ambulances in order to hide the true number of cases.

It took officials at least four months to institute any quarantine measures.

China says it has since learned its lesson and has made sharing information a priority.

Authorities have reacted by locking down Wuhan and more than a dozen other cities across Hubei province, restricting the movement of 56 million people.

Has a vaccine been developed?

There is not currently a vaccine available for either SARS or the Wuhan virus.

A vaccine was prepared for human trials following the SARS outbreak, but it was never needed as the virus was able to be contained.

Please use Chrome browser for a more accessible video player

Coronavirus: What you need to know

As scientists have already worked on vaccines for other strains of coronavirus, including Middle East respiratory syndrome (MERS), there is optimism a vaccine for 2019-nCoV could be developed by the summer.

Virologist Professor Paul Kellam previously told Sky News: "If everything moves smoothly, it takes three to six weeks to get to the point where you can start testing, then you look to see if they can raise an immune response, normally in an animal.

"You won't start to get human studies until about the beginning of the summer, probably July. But, it's a bit of a moveable feast."

Coronavirus outbreak: Patients arrive at China's new hospital as death toll reaches 362


If the Wuhan virus is not able to be contained and a vaccine is not developed, it could become endemic - meaning deaths would occur each year as the virus circulates.

But with scientists still trying to record more accurate data on the latest outbreak, there is not yet solid evidence as to how severe and contagious this strain of coronavirus is - and whether it could be as deadly as the SARS pandemic.