Are coronavirus diseases equally deadly?
By: Jiachuan Wu and Denise Chow
A coronavirus outbreak that emerged in China in December, and is now spreading into other countries, has sickened more than 90,000 people (mostly in China) and killed more than 3,000. Public health officials are racing to contain the pathogen, but this is not the first time the world has had to battle the spread of a novel coronavirus. Here's how the current situation compares to past epidemics.
The new coronavirus, which causes a disease called COVID-19, was first reported in Wuhan, China. It has now spread to more than 60 countries, including South Korea, Japan, Italy, Iran and the United States.
The source of the virus has not been confirmed, but early genetic analyses suggest that the pathogen likely originated in bats and was subsequently passed to an intermediate animal before spilling over into humans.
SARS, or severe acute respiratory syndrome, was first identified in November 2002 in the Guangdong province of southern China. The viral respiratory illness, caused by a coronavirus, spread to 26 countries in North America, South America, Europe and Asia before it was contained in July 2003.
The virus is thought to have spread likely from bats to civet cats — small mammals that resemble weasels — before the first human patient was infected.
During the outbreak, there were 8,098 reported cases of SARS and 774 deaths. Infections were primarily through person-to-person transmissions. No known cases of SARS have been reported since 2004, according to the Centers for Disease Control and Prevention .
MERS, or Middle East respiratory syndrome, was first reported in Saudi Arabia in 2012. The respiratory illness is caused by a coronavirus, a distant viral cousin to SARS. It spread to 27 countries in Europe, Africa, Asia and North America.
Like many coronaviruses, MERS is a zoonotic virus, which means it is transmitted between animals and humans. According to scientists, MERS most likely passed from bats into dromedary camels before jumping to humans.
Since 2012, there have been 2,494 reported cases of MERS, and 858 deaths from the virus. Infections occurred primarily from close human-to-human contact, according to the World Health Organization .
The new coronavirus appears to be less deadly than SARS, which killed around 10 percent of people who became infected. The SARS outbreak was contained within about six months, while the COVID-19 outbreak is only a few months old at this point. Approximately 35 percent of reported patients with MERS died, but there were significantly fewer cases than either SARS or COVID-19 during that outbreak.
Because the latest coronavirus outbreak is still unfolding globally, scientists don’t yet know the virus’ true fatality rate. On March 3, WHO Director-General Dr. Tedros Adhanom Ghebreyesus said that 3.4 percent of reported cases have died so far , but as the outbreak evolves, that number is likely to change.
The percentages below show the number of cases broken down by age groups. The COVID-19 numbers only represent reported cases from China through Feb. 11, 2020.
The new coronavirus is structurally similar to SARS, with the two viruses sharing about 80 percent of their genomes , according to Timothy Sheahan, an epidemiologist at the Gillings School of Global Public Health at the University of North Carolina.
Genetic analyses have also shown that the coronavirus has not undergone many significant changes since it first emerged in Wuhan. As viruses pass from person to person and spread into new geographical locations, it’s not uncommon for them to mutate to avoid dying out.
“It’s basically Darwinian evolution, where it’s survival of the fittest,” Sheahan said. “But if you already have a virus that is good at human-to-human transmission and good at replicating in a person, there’s no reason for it to get more fit.”