India 'misleading the public' on Sikkim stand-off, says China

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.

Canadian researchers are developing a DNA vaccine for SARS-CoV-2, the coronavirus that causes COVID-19 and has currently infected nearly 5,00,000 people worldwide and crippled the global economy.

Entos Pharmaceuticals, a health-care biotechnology company headed by a University of Alberta researchers, develop new therapeutic compounds using the company's proprietary drug-delivery platform and has begun manufacturing vaccine candidates against the novel coronavirus.

"Given the urgency of the situation, we can have a lead candidate vaccine within two months. Once we have that it's a race to get it into clinical trials," said John Lewis, CEO of Entos and a Professor at the University of Alberta in Canada.

Lewis said in comparison to a traditional vaccine, DNA-based vaccines hold several advantages.

Nucleic acids are introduced directly into the patient's own cells, causing them to make pieces of the virus--tricking the immune system into mounting a response without the full virus actually being present, the researcher said.

According to the company, the approach is recognised as being easier to move into large-scale manufacturing, offers improved vaccine stability and works without needing an infectious agent.

In the current absence of a vaccine for COVID-19, several companies around the world are mounting efforts to begin similar work.

The first clinical trial using a DNA-based vaccine developed by Moderna Inc.in the US on March 13.

Their approach allows for antibodies to be made in the human trial volunteers against a specific protein on the surface of the coronavirus that lets the virus enter human cells.

The hope is that the antibodies will stop the interaction.

Though this approach is designed to be effective against COVID-19 specifically, Lewis said Entos is taking a different tack.

The company plans to use plasmid DNA to amplify the production of key coronavirus surface and structural proteins with each injection, with an eye to the bigger picture.

"Many of the structural proteins in the virus are pretty well conserved across all the coronaviruses, including SARS and MERS," said Lewis.

"We're hoping that if we express more of the structural proteins that are common to most coronaviruses, we can inhibit the current COVID-19, and also potentially protect against all coronaviruses both past and future," Lewis added.

To move the project forward quickly, the company is seeking financial support from both provincial and federal levels of government.

"We have the opportunity to save a lot of lives, and I think it's really upon us and governments to find solutions for that," Lewis said.

Beijing, Mar 24:  China reported 78 new confirmed cases, including 74 imported infections, while the death toll from the novel coronavirus increased to 3,277 after seven more fatalities were confirmed from the COVID-19, health officials said on Tuesday.

The overall confirmed cases on the Chinese mainland have reached 81,171 by the end of Monday. This included 3,277 people who died of the disease, 4,735 patients who were still being treated and 73,159 patients discharged after recovery, the National Health Commission (NHC) said on Tuesday.

The NHC said, 78 new confirmed COVID-19 cases were reported on the Chinese mainland on Monday, of which 74 were imported from abroad taking the number of overseas cases to 427.

Also on Monday, seven deaths and 35 new suspected cases were reported on the mainland with all the deaths in Hubei Province.

The total COVID-19 cases in Beijing climbed to 522 with eight deaths prompting local governments of Beijing as well as Shanghai to announce that all overseas arrivals will be subjected to nucleic acid tests to ensure proper detection.

Of the 74 newly imported cases, 31 were reported in Beijing, 14 in Guangdong, nine in Shanghai, five in Fujian, four in Tianjin, three in Jiangsu, two in Zhejiang and Sichuan respectively, and one in Shanxi, Liaoning, Shandong and Chongqing respectively, the NHC said.

Beijing is already diverting all international flights to different cities where the passengers will be quarantined for 14 days before arriving in the city.

The NHC said 132 people were still suspected of being infected with the virus.

Coronavirus epicentre Wuhan has reported one confirmed case after a gap of five days prompting officials to begin to ease restrictions.

Wuhan also reported seven new deaths, bringing the total number of deaths in the city and Hubei province for which Wuhan is the capital to 3,160.

The province also saw 444 patients discharged from hospital after recovery on Monday. Among the 4,200 patients being treated in hospital, 1,203 were still in severe condition and another 336 in critical condition, the local health commission said.

By the end of Monday, 356 confirmed cases, including four deaths have been reported in Hong Kong, which has restricted the entry of foreigners into the city. Also a total of 25 confirmed cases were reported in Macao and 195 in Taiwan including two deaths, state-run Xinhua news agency reporrted.

After days of decline in coronavirus cases, China on Monday said that COVID-19 has effectively been "stemmed" in the country and it started easing severe restrictions imposed on Wuhan's 11 million people who were under lockdown since January 23.

The authorities began relaxing restrictions in Wuhan as it reported no new case for the fifth consecutive day on Monday.

Significantly, the Central Leading Group (CLP), headed by Premier Li Keqiang which is coordinating efforts to contain the virus since January 23, said the virus has been curtailed in the country as well as in Wuhan.

"The meeting noted that the spread of the virus nationwide, particularly in the epicentre of Wuhan, has been effectively stemmed," an official statement said on Monday.

The meeting, however, warned that the risks for sporadic infections and localised outbreaks have not gone away. With the pandemic rampaging across the world, the situation remains complex and challenging.

"Wuhan city and Hubei province should stay focused on medical treatment and community-level containment as the two key priorities. They should continue to treat the severe cases, promptly admit new cases, and advance epidemiological investigations," the meeting said.

In Wuhan, officials said people are allowed to go back to work while restrictions on the public transport are gradually being eased.

The Hubei province and its capital Wuhan with over 56 million people were under lockdown since January 23. The vicious virus broke out in city, reportedly at a live animal market in December last year and became virulent inflicting thousands of people in the city and province catching the government off guard.

As the country saw a surge in imported infections, the Chinese government announced that all international flights scheduled to arrive in Beijing will be redirected to airports in 12 other Chinese cities from Monday.

International passengers flying to Beijing will instead land at airports in 12 cities including Shanghai, Tianjin, Nanjing and Shenyang as their first points of entry, the Civil Aviation Administration of China (CAAC) said in a statement.

On Monday, China said international travellers should "think twice" about choosing Beijing for flight transfer in view of the restrictions.

Starting from Monday, all international flights scheduled to arrive in Beijing will be redirected to airports in 12 other Chinese cities, Liu Haitao, an official with China's National Immigration Administration said.

Passengers would go through entry procedures and quarantine measures at the designated cities' airports before they continue their flights to Beijing, Liu said, urging travellers to reserve enough time for their next flights to make sure that they do not miss their outbound flights.