Tsunami hits Japan after strong quake, nuclear plant briefly disrupted

The head of the World Health Organisation on Tuesday warned the novel coronavirus was a "very grave threat" for the world as he opened a conference to combat the epidemic.

"With 99% 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," Tedros Adhanom Ghebreyesus said in Geneva.

Some 400 scientists will review how the virus is transmitted and possible vaccines at the two-day forum.

"What matters most is stopping the outbreak and saving lives. With your support, that's what we can do together," Tedros said.

The virus, first identified in China on December 31, has killed more than 1,000 people, infected over 42,000 and reached some 25 countries.

Participants will also discuss the source of the virus, which is thought to have originated in bats and reached humans via another animal such as snakes or pangolins.

There is no specific treatment or vaccine against the virus, which can cause respiratory failure.

Tedros, who has repeatedly urged countries affected to share their data, called for global "solidarity".

"That is especially true in relation to the sharing of samples and sequences. To defeat this outbreak, we need open and equitable sharing, according to the principles of fairness and equity," he said.

"We hope that one of the outcomes of this meeting will be an agreed roadmap for research around which researchers and donors will align," Tedros said.

Several companies and institutes in Australia, China, France, Germany and the United States are racing to develop a vaccine -- a process that normally takes years.

Asked whether scientists from Taiwan would be allowed to take part in this week's Geneva conference, WHO officials said that they would do so but only online -- along with colleagues from other parts of China.

While the WHO does not deal with Taiwan directly and only recognises Beijing, Taiwan was often allowed to attend annual assemblies and sideline meetings as an observer.

But in recent years it has been frozen out as Beijing takes an increasingly combative stance towards democratic Taiwan, which it considers its own territory.

May 20: The novel coronavirus is behaving differently in patients in northeast China who have contracted it recently compared with early cases, indicating it is changing as it spreads, a prominent doctor said.

China, which has largely brought the virus under control, has found new clusters of infections in the northeastern border provinces of Jilin and Heilongjiang in recent weeks, raising concern about a second wave.

Qiu Haibo, an expert in critical care medicine who is part of a National Health Commission expert group, said the incubation period of the virus in patients in the northeast was longer than that of patients in Wuhan, the central city, where the virus emerged late last year.

COVID-19 Pandemic Tracker: 15 countries with the highest number of coronavirus cases, deaths

"This causes a problem, as they don't have any symptoms. So when they gather with their families they don't care about this issue and we see family cluster infections," Qiu told state broadcaster CCTV in a programme broadcast late on Tuesday.

Patients in the northeastern clusters were also carrying the virus for longer than earlier cases in Wuhan, and they were taking longer to recover, as defined by a negative nucleic acid test, he said.

Patients in the northeast also rarely exhibited fever and tended to suffer damage to the lungs rather than across multiple organs, he said.

He said the virus found in the northeastern clusters was probably imported from abroad, which could account for the differences.

He did not say where he though they might have come from but both Jilin and Heilongjiang border Russia.

China reported five new coronavirus cases on Wednesday, down from six a day earlier.

Four of the new cases were local transmissions and one was imported by a traveller coming from abroad, the commission said in a statement, compared with three imported cases reported the previous day.

China's total number of coronavirus infections stands at 82,965, while the death toll 4,634. 

Houston, Mar 15: Researchers, studying the novel coronavirus, have found that the time between cases in a chain of transmission is less than a week, and over 10 per cent of patients are infected by someone who has the virus, but does not show symptoms yet, a finding that may help public health officials contain the pandemic.

The study, published in the journal Emerging Infectious Diseases, estimated what's called the serial interval of the coronavirus by measuring the time it takes for symptoms to appear in two people with the virus -- the person who infects another, and the infected second person.

According to the researchers, including those from the University of Texas at Austin, the average serial interval for the novel coronavirus in China was approximately four days.

They said the speed of an epidemic depends on two things -- how many people each case infects, and how long it takes cases to spread.

The first quantity, the scientists said, is called the reproduction number, and the second is the serial interval.

Due to the short serial interval of the disease caused by the coronavirus -- COVID-19 -- they said, emerging outbreaks will grow quickly, and could be difficult to stop.

“Ebola, with a serial interval of several weeks, is much easier to contain than influenza, with a serial interval of only a few days,” said Lauren Ancel Meyers, study co-author from UT Austin.

Meyers explained that public health responders to Ebola outbreaks have much more time to identify and isolate cases before they infect others.

“The data suggest that this coronavirus may spread like the flu. That means we need to move quickly and aggressively to curb the emerging threat,” Meyers added.

In the study, the scientists examined more than 450 infection case reports from 93 cities in China, and found the strongest evidence yet that people without symptoms must be transmitting the virus -- known as pre-symptomatic transmission.

More than one in ten infections were from people who had the virus but did not yet feel sick, the scientists said.

While researchers across the globe had some uncertainty until now about asymptomatic transmission with the coronavirus, the new evidence could provide guidance to public health officials on how to contain the spread of the disease.

“This provides evidence that extensive control measures including isolation, quarantine, school closures, travel restrictions and cancellation of mass gatherings may be warranted,” Meyers said.

The researchers cautioned that asymptomatic transmission makes containment more difficult.

With hundreds of new cases emerging around the world every day, the scientists said, the data may offer a different picture over time.

They said infection case reports are based on people's memories of where they went and whom they had contact with, and if health officials move quickly to isolate patients, that may also skew the data.

“Our findings are corroborated by instances of silent transmission and rising case counts in hundreds of cities worldwide. This tells us that COVID-19 outbreaks can be elusive and require extreme measures,” Meyers said.