The continued spread of the deadly coronavirus that originated in Wuhan, China, is often compared with the severe acute respiratory syndrome (Sars) epidemic of nearly two decades ago that affected more than 8,000 people in 37 countries. The comparison became more acute on Thursday when the World Health Organisation (WHO) designated the new coronavirus a global public health emergency , fuelling public anxiety. According to Chinese health authorities, 259 people have succumbed to the new virus, with thousands more cases reported on the mainland. So far, almost 12,000 people have been infected, far exceeding that of the 2002-03 Sars epidemic. The two viruses share similar symptoms. Carriers of the latest coronavirus experience fever, malaise, dry cough, shortness of breath and occasionally respiratory distress, according to a number of medical journals. The virus carriers’ vital signs have been stable in most cases, but leukopenia, a decrease in white blood cells, and lymphopenia, a reduction in the white blood cells known as lymphocytes, were common, studies say. Similarly, Sars also usually brings with it flu-like signs – including fever, chills, muscle aches, headache and occasionally diarrhoea. Both viruses are known to cause pneumonia. The genetic sequence of the latest coronavirus is at least 70 per cent similar to Sars, according to medical journals. Both belong to the large coronavirus family which causes illnesses ranging from the common cold to more severe diseases. Transmission According to the WHO, both viruses are zoonotic – transmissible from animals to humans. Although the scientific research is ongoing, some studies suggest bats are the most likely hosts for the virus' origins, although it could not have been transmitted directly to humans. Researchers have compared the new coronavirus’ genetic sequence with those in a library of viral sequences, and found that the most closely related viruses were coronaviruses that originated in bats . The Chinese Centre for Disease Control (CDC) said it analysed samples of 15 animals from the seafood market thought to be at the centre of the outbreak, but found no match. Yet, WHO says Sars is only “thought to be” an animal virus from an “as-yet-uncertain” animal reservoir – perhaps bats – which spread to other animals such as civet cats. Sars was thought to be transmitted most readily by respiratory droplets produced when an infected person coughed or sneezed. Paper on human transmission of coronavirus sets off social media storm The Sars virus can also spread when a person touches a surface or object contaminated with infectious droplets and then touches his or her mouth, nose, or eyes, according to data compiled by the CDC. There is a possibility the new coronavirus may also be an airborne disease, but further studies are needed for conclusive results. Reproduction Scientists have been looking to pinpoint just how contagious the new virus is, using a measurement called the “reproduction number”, which signifies how many people a sick person can infect. The rate for Sars, according to the WHO, ranges from two to five depending on transmission settings, with researchers often citing the two to three range. Recent studies of the new coronavirus have said its reproduction number is looking similar – about two or three – based on initial studies, although the WHO preliminary estimate was slightly lower at 1.4 and 2.5. Experts caution that in the early stages these numbers are difficult to calculate as the number of cases continues to change, which has an impact on the statistical models. Containment efforts can also influence the reproduction number as the outbreak goes on, according to virologist Ian Mackay, an associate professor at the University of Queensland in Australia. Coronavirus stokes worry over job losses in China’s thriving service sector “The number will probably drop as we see containment efforts have more of an effect,” he said, noting this was because people, especially those exhibiting symptoms, would take more disease prevention precautions and seek treatment. Differences The new virus is clinically milder than Sars in terms of severity, case fatality rate and transmissibility, according to medical data. So far, the mortality rate for the new virus is about 2 per cent – with 259 deaths out of the 10,000 people infected. Meanwhile, the Sars outbreak infected 8,437 people worldwide with a mortality rate of 10 per cent. According to a WHO report, the deaths of 813 people were attributed to the Sars virus between November 1, 2002 and July 11, 2003. Contagion Nevertheless, the scale of the outbreak of the new coronavirus has already exceeded Sars, with the number of infected patients already outstripping the previous health emergency. Another factor complicating prevention is the suggestion that the new coronavirus, unlike Sars, is transmissible even by people who are not showing any symptoms. At a press conference on Sunday, China’s National Health Commission said the virus, unlike its predecessor, was contagious even during the incubation period which lasts up to 14 days. Purchase the China AI Report 2020 brought to you by SCMP Research and enjoy a 20% discount (original price US$400). This 60-page all new intelligence report gives you first-hand insights and analysis into the latest industry developments and intelligence about China AI. Get exclusive access to our webinars for continuous learning, and interact with China AI executives in live Q&A. Offer valid until 31 March 2020.