China confirms person-to-person spread of new virus as fourth person death reported

Beijing, May 24: The Chinese virology institute in the city where COVID-19 first emerged has three live strains of bat coronavirus on-site, but none match the new contagion wreaking chaos across the world, its director has said.

Scientists think COVID-19 -- which first emerged in Wuhan and has killed some 340,000 people worldwide -- originated in bats and could have been transmitted to people via another mammal.

But the director of the Wuhan Institute of Virology told state broadcaster CGTN that claims made by US President Donald Trump and others that the virus could have leaked from the facility were "pure fabrication".

"Now we have three strains of live viruses... But their highest similarity to SARS-CoV-2 only reaches 79.8 percent," she said, referring to the coronavirus strain that causes COVID-19.

US demands immediate start to WHO review

The United States called on the World Health Organisation on Friday to begin working immediately on investigating the source of the novel coronavirus, as well as its handling of the response to the pandemic.

One of their research teams, led by Professor Shi Zhengli, has been researching bat coronaviruses since 2004 and focused on the "source tracing of SARS", the strain behind another virus outbreak nearly two decades ago.

"We know that the whole genome of SARS-CoV-2 is only 80 percent similar to that of SARS. It's an obvious difference," she said.

"So, in Professor Shi's past research, they didn't pay attention to such viruses which are less similar to the SARS virus."

Conspiracy rumours that the biosafety lab was involved in the outbreak swirled online for months before Trump and US Secretary of State Mike Pompeo brought the theory into the mainstream by claiming that there is evidence the pathogen came from the institute.

The lab has said it received samples of the then-unknown virus on December 30, determined the viral genome sequence on January 2 and submitted information on the pathogen to the WHO on January 11.

Wang said in the interview that before it received samples in December, their team had never "encountered, researched or kept the virus."

"In fact, like everyone else, we didn't even know the virus existed," she said. "How could it have leaked from our lab when we never had it?"

The World Health Organization said Washington had offered no evidence to support the "speculative" claims.

In an interview with Scientific American, Shi said the SARS-CoV-2 genome sequence did not match any of the bat coronaviruses her laboratory had previously collected and studied.

Dhaka, Jan 3: Bangladesh's paramilitary force chief said on Thursday that a total of 445 Bangladeshi nationals returned from India in last two months following the publication of the National Register of Citizens (NRC) by the Indian government.

Border Guard Bangladesh (BGB) Director General Maj Gen Md Shafeenul Islam disclosed the figure during a press briefing here.

"About 1,000 people were arrested in 2019 for illegal border crossings from India to Bangladesh, with 445 of them returning home in November and December," he said.

After verifying their identities through local representatives, BGB came to know that all the intruders are Bangladeshis, Islam said, adding that 253 cases were lodged against them for illegal trespass, while initial investigations found that at least three of them were human traffickers.

The BGB Director said the trespassing did not create any tension between the border forces of Bangladesh and India.

Last week, Islam visited India where he said that the creation of the NRC is completely an "internal affair" of India and the cooperation between the border guarding forces of the two countries is very good.

He said the BGB will continue to do its work of preventing illegal border crossings as per its mandate.

A BGB delegation, led by Islam, was on a bilateral visit to India to hold DG-level border talks with its counterparts, the Border Security Force (BSF).

The talks took place from December 26-29, during which a host of issues related to cross-border smuggling and activities of criminals and others along the 4,096-km-long front were discussed.

Responding to a question, Islam said, "No discussion was held at the conference over the (NRC) issue".

He said during the five-day talks held in New Delhi, the BGB demanded that the BSF should take effective steps to prevent killings of Bangladeshis on frontiers as casualty figures sharply rose in 2019.

"The number of border killings in 2019 was highest in the last four years. As per our calculation, the number of such unexpected deaths was 35," the BGB chief said.

However, the BSF estimate of the casualty figure is much lower than our calculation, he said.

Islam said the BSF is following the policy of maintaining maximum restraint and minimal use of force even after being attacked by "armed border offenders".

A statement issued by the BSF last month in New Delhi after the conclusion of the DG-level talks said, "On the concern of the BGB regarding the death of Bangladeshi nationals on borders, it was informed to them that a non-lethal weapon policy is strictly followed by BSF personnel on borders.

"Firing is resorted to only in self-defence, when BSF patrols are gheraoed and attacked by ‘dah’ (a sharp-edged weapon) etc. It was specified that the BSF does not discriminate between criminals based on nationality," it said.

London, May 20: The current physical distancing guidelines of 6 feet may be insufficient to prevent COVID-19 transmission, according to a study which says a mild cough in low wind speeds can propel saliva droplets by as much as 18 feet.

Researchers, including those from the University of Nicosia in Cyprus, said a good baseline for studying the airborne transmission of viruses, like the one behind the COVID-19 pandemic, is a deeper understanding of how particles travel through the air when people cough.

In the study, published in the journal Physics of Fluids, they said even with a slight breeze of about four kilometres per hour (kph), saliva travels 18 feet in 5 seconds.

"The droplet cloud will affect both adults and children of different heights," said study co-author Dimitris Drikakis from the University of Nicosia.

According to the scientists, shorter adults and children could be at higher risk if they are located within the trajectory of the saliva droplets.

They said saliva is a complex fluid, which travels suspended in a bulk of surrounding air released by a cough, adding that many factors affect how saliva droplets travel in the air.

These factors, the study noted, include the size and number of droplets, how they interact with one another and the surrounding air as they disperse and evaporate, how heat and mass are transferred, and the humidity and temperature of the surrounding air.

In the study, the scientists created a computer simulation to examine the state of every saliva droplet moving through the air in front of a coughing person.

The model considered the effects of humidity, dispersion force, interactions of molecules of saliva and air, and how the droplets change from liquid to vapour and evaporate, along with a grid representing the space in front of a coughing person.

Each grid, the scientists said, holds information about variables like pressure, fluid velocity, temperature, droplet mass, and droplet position.

The study analysed the fates of nearly 1,008 simulated saliva droplets, and solved as many as 3.7 million equations.

"The purpose of the mathematical modelling and simulation is to take into account all the real coupling or interaction mechanisms that may take place between the main bulk fluid flow and the saliva droplets, and between the saliva droplets themselves," explained Talib Dbouk, another co-author of the study.

However, the researchers added that further studies are needed to determine the effect of ground surface temperature on the behaviour of saliva in air.

They also believe that indoor environments, especially ones with air conditioning, may significantly affect the particle movement through air.

This work is important since it concerns safety distance guidelines, and advances the understanding of the transmission of airborne diseases, Drikakis said.