Coronavirus 'super-spreaders' a potential risk as strain spreads from Wuhan to cities outside of China
PHOTO An expert in China said one ill patient spread the virus to 14 medical professionals. AP: MARK SCHIEFELBEIN
One of China's top health experts is warning of the potential for "super-spreaders" to worsen the impact of the new coronavirus strain, which can now be passed from human to human.
Zhong Nanshan, the leader of an expert team sent to Wuhan to investigate the virus, told the South China Morning Post there was evidence one patient alone had spread the virus to 14 medical workers.
As of January 20, there were more than 300 confirmed cases of the
new coronavirus in China and elsewhere, however they have been mostly concentrated in Wuhan, where six people have died.
A Brisbane man was tested for the strain after returning from Wuhan with flu-like symptoms, but he was released from home isolation shortly after because he exhibited no symptoms of the virus. Queensland Health is still waiting on additional tests.
Dr Zhong said stopping the emergence of super-spreaders was "key to controlling the spread of the virus", but with the busy Lunar New Year travel period underway an increase in infections was expected.
So what exactly is a super-spreader, and what can be done to prevent them
infecting other people?
Here's what you need to know.
What is a super-spreader?
A super-spreader is essentially a person who, for a number of reasons, spreads an infectious disease to many other people, frequently the medical workers treating them.
PHOTO Medical workers are often most affected by super-spreaders. REUTERS
Kanta Subbarao, the director of the WHO Collaborating Centre for Reference and Research on Influenza at the Peter Doherty Institute for Infection and Immunity, told the ABC the term first really came into use during
the 2002-2003 SARS coronavirus outbreak.
"With many viruses that transmit from person to person, there's a general idea of how many people can be infected from the same source," she said.
"With the super-spreaders — particularly with SARS — it became clear that there were some individuals, a few people, whose infections led to a larger number of secondary infections.
"That's what people watch for when novel viruses emerge: whether there are some people who might serve as a source for larger dissemination, or dissemination to a larger number of people than others."
Professor Subbarao said these secondary infections largely affected the healthcare workers treating the patients, as well as other people they had been in contact with.
Allen Cheng, an infectious disease and epidemiology expert at Monash University, said it was not known if these secondary infections had to do with the amount of SARS virus super-spreaders were shedding, or if it was because they had come into contact with a lot of people.
Have any super-spreaders been identified?
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Video 0:23
Medics check the temperatures of passengers on a flight from Wuhan to Macau.
ABC News
Not yet — and thankfully super-spreaders are rare, according to Professor Subbarao.
Professors Cheng and Subbarao said it remained unclear if super-spreaders would even be a factor in the Wuhan coronavirus outbreak because information was still emerging, including on the total number of potential infections.
"This is early days; we don't have a lot of information yet and we're all waiting to see more of the facts as they emerge in scientific publications," Professor Subbarao said.
"Trying to figure out if there are super-spreaders will really require a lot more epidemiologic information than we currently have.
"I'm sure this is an area that [health authorities] are looking into quite closely."
Unfortunately, super-spreaders can only be identified after they have infected a large number of people.
However Professor Subbarao said she thought it would be quite unusual for a super-spreader to not show any symptoms of illness because they usually ended up in hospitals or other health facilities.
"What we learned from the SARS outbreak … and we learned this with the MERS coronavirus as well … is that the people that have been the source of large numbers of infection have been symptomatic and they've often been in medical care facilities," she said
Lunar New Year travel a risk factor
Celebrations around the Lunar New Year spring festival are adding an extra element of risk to the situation.
PHOTO There are fears the Lunar New Year travel period could see infection rates rise. AP: MARK SCHIEFELBEIN
The annual event sees the largest annual movement of people in the world. During the festival, people from all over China travel back to their hometowns to spend time with family, creating huge pressure on the country's public transport networks.
This means billions of train trips over a matter of days, with tickets at packed train stations often hard to come by. Some people also use the holiday period to travel abroad.
"It's certainly something that potentially could lead to spread when people travel, and if they're incubating the virus or ill with it, and yet they travel, they may expose many more people to the pathogen," Professor Subbarao said.
"We don't have a great handle on the incubation period, so people could make their plans and travel before they become symptomatically ill."
PHOTO Train stations often become extremely crowded during the spring festival rush. CHINATOPIX VIA AP
With the situation still evolving, Professor Subbarao said experts were waiting for more facts to emerge about the new coronavirus strain.
"There's no reason to panic, but on the other hand we are all waiting for more information," she said.
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