BBC: "Super-spreaders" scatter corona virus worldwide; WHO: A serious threat

BBC: "Super-spreaders" scatter corona virus worldwide; WHO: A serious threat

The coronavirus outbreak poses a "very grave threat for the rest of the world", the head of the World Health Organization (WHO) said in an appeal for sharing virus samples and speeding up research into drugs and vaccines against a new type of coronavirus, which has killed more than 1,000 people so far.

"With 99 percent of cases in China, this remains very much an emergency for that country, but one that holds a very grave threat for the rest of the world," WHO Director-General Tedros Adhanom Ghebreyesus said in opening remarks to a meeting of more than 400 researchers and national authorities, opening a two-day WHO World Forum in Geneva.

The "peak" of the outbreak in late February

The coronavirus epidemic could peak by the end of February, after which it will begin to decline, the Chinese government's chief medical adviser said today.

In an exclusive interview with Reuters news agency, Zhong Nanshan, a leading epidemiologist who won international fame for his role in combating the SARS epidemic in 2003, said the situation in some provinces was already improving, with the number of new cases declining.

Zhong, who had previously predicted an earlier peak, said the forecast was based on modelling and developments in recent days, as well as government action. However, the BBC writes that the real danger lies in the virus super-spreaders.

Super-spreading, where individual patients pass on an infection to large numbers of people, is a feature of nearly every outbreak. It is not their fault but can have a significant impact on how diseases spread. There are reports of super-spreading during the new coronavirus outbreak.

Namely, one British national who had been in Singapore, has been linked to four cases in the UK, five in France and possibly one in Mallorca.

On average, each person infected with the new coronavirus is passing it on to between two and three other people. But this is only an average; some people will pass it on to nobody while others pass their infection on to far more.

Back in 2015, a super-spreading event led to 82 people being infected from a single hospital patient with Middle East respiratory syndrome (Mers).

And in the Ebola epidemic in West Africa, the vast majority of cases came from just a tiny handful of patients.

"There were more than 100 new chains of transmission from just one funeral in June 2014", Dr Nathalie MacDermott, from King's College London, claims.

Some just come into contact with far more people, either because of their job or where they live, and that means they can spread more of the disease, whether or not they themselves have symptoms.

"Kids are good at that - that's why closing schools can be a good measure," Dr John Edmunds, from the London School of Hygiene and Tropical Medicine, says.

Others are "super-shedders", who release unusually large amounts of virus from their bodies, so anybody coming into contact with them is more likely to become infected.

Hospitals treating severe acute respiratory syndrome (SARS) became a major centre of super-spreading because the sickest patients were also the most infectious and they came into contact with lots of healthcare workers.

"It plays a big role at the beginning of any outbreak, when the virus is trying to get established," Dr Edmunds told BBC News. When it makes the jump into the first patient, the disease might fizzle out before it can cause a large outbreak, but if it can quickly find its way into a super-spreader, then it gives the outbreak a boost.

Super-spreading was known in the past as well - back in the 19th and 20th century, an Irish woman unknowingly passed typhoid fever on to 51 person, when she had no symptoms, while some twenty years ago, a high school student from Finland infected as many as 22 people with measles.