Coronavirus super-spreaders pose urgent threat and need to be tracked
While most infected patients usually infect two or three people on an average, superspreaders could infect dozens
A British coronavirus patient is believed to have passed on his infection to 11 others from three countries. And in Wuhan, another infected patient may have transmitted the virus to over 10 heath workers and 4 other patients in a hospital. Called Superspreaders, these individuals are capable of infecting dozens. By comparison, most infected patients usually infect two or three people.
Superspreaders are capable of passing a pathogen — bacteria or virus — to an unusually large number of people. Scientists estimate that these people, who constitute 20% of the population, are usually responsible for over 80% of all confirmed infections.
They have also played a key role in the outbreaks of other coronaviruses, including SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome).
"A traveler sick with SARS and staying in a Hong Kong hotel infected several overseas guests who then returned home and introduced the virus into four other countries," Elizabeth McGraw, Professor of Entomology and Director of the Center for Infectious Disease Dynamics, Pennsylvania State University, wrote in The Conversation.
What is more, superspreaders make it hard to contain outbreaks. So scientists set out to determine whether superspreaders are part of the picture during an outbreak because they tend to accelerate the rate of new infections, according to McGraw. Further, tracking them can help officials recommend various ways to contain their impact and slow the spread of disease, depending on how the pathogen is transmitted.
What do we know of the Coronavirus superspreaders?
Ever since the outbreak took off, scientists have been keeping a keen eye for superspreaders. And the British man's case could be a well-established one.
For now, scientists know that the 50-year-old man is believed to have contracted the virus while attending a conference in Singapore. He later is said to have infected 11 others from three different countries. It is also believed that the British man may have been infected by another superspreader attending the conference from Wuhan.
Why only a few people become superspreaders?
Scientists are yet to understand why a small set of people that get infected turn out to be superspreaders. Some speculate that an individual's immune system could play a role.
"Highly tolerant people do not feel sick and so may continue about their daily routines, inadvertently infecting more people. Alternatively, people with weaker immune systems that allow very high amounts of virus replication may be very good at transmitting even if they reduce their contact with others," McGraw said.
But what they do know is that they play a big role at the beginning of an outbreak "when the virus is trying to get established," Dr John Edmunds, from the London School of Hygiene and Tropical Medicine, told BBC News.
To contain the spread, scientists need to track superspreaders. "It makes that even more important - you can't afford too many mistakes, you can't afford to miss the superspreader," Prof Mark Woolhouse, from the University of Edinburgh, told BBC.