Trump asks Supreme Court to reinstate Muslim travel ban

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.

Washington, Mar 8: An attendee at last week's Conservative Political Action Conference (CPAC), which also saw the participation of US President Donald Trump, has tested positive for COVID-19, the American Conservative Union (ACU) said.

The exposure occurred prior to the conference held in National Harbor, Maryland, just south of Washington D.C., Xinhua news agency quoted the ACU as saying in a statement on Saturday.

A New Jersey hospital tested the person, and the Centers for Disease Control and Prevention (CDC) confirmed the positive result, said the statement.

"The individual is under the care of medical professionals in the state of New Jersey, and has been quarantined," it said.

Trump and Vice President Mike Pence spoke at the gathering, which took place from February 26-29.

Also present at the event were a number of administration and cabinet officials, including Secretary of State Mike Pompeo, Health and Human Services Secretary Alex Azar, and newly-appointed White House Chief of Staff Mark Meadows.

White House Press Secretary Stephanie Grisham said in a statement Saturday that the White House was aware of the development.

"At this time there is no indication that either President Trump or Vice President Pence met with or were in close proximity to the attendee," Grisham said in a statement.

"The President's physician and US Secret Service have been working closely with White House Staff and various agencies to ensure every precaution is taken to keep the First Family and the entire White House Complex safe and healthy."

The news emerged as Washington D.C. and neighbouring state of Virginia respectively confirmed their first cases of COVID-19 on Saturday.

In a press conference on Saturday night, Washington D.C. Mayor Muriel Bowser said a resident in his 50s showed symptoms of a respiratory virus in February. He was admitted to a hospital in the District on March 5.

The patient had no history of recent international travel, nor had he been exposed to anyone who was confirmed to be infected, according to Bowser.

The Mayor said D.C. health authorities were investigating the man's contact with other people before he went to the hospital.

A US Marine assigned to Fort Belvoir in Fairfax County, Virginia, tested positive on Saturday for COVID-19 and is currently being treated at Fort Belvoir Community Hospital, according to a Pentagon spokesman.

"The Marine recently returned from overseas where he was on official business," tweeted Jonathan Rath Hoffman, adding that Secretary of Defence Mark Esper and the White House have been briefed.

As of Saturday night, more than 420 cases of COVID-19 were reported in the US with 17 deaths, according to the Center for Systems Science and Engineering at Johns Hopkins University.

Feb 22: A 20-year-old Chinese woman from Wuhan, the epicentre of the coronavirus outbreak, travelled 400 miles(675 km) north to Anyang where she infected five relatives, without ever showing signs of infection, Chinese scientists reported on Friday, offering new evidence that the virus can be spread asymptomatically.

The case study, published in the Journal of the American Medical Association, offered clues about how the coronavirus is spreading, and suggested why it may be difficult to stop.

"Scientists have been asking if you can have this infection and not be ill? The answer is apparently, yes," said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, who was not involved in the study.

China has reported a total of 75,567 cases of the virus known as COVID-19 to the World Health Organization (WHO) including 2,239 deaths, and the virus has already spread to 26 countries and territories outside of mainland China.

Researchers have reported sporadic accounts of individuals without any symptoms spreading the virus. What's different in this study is that it offers a natural lab experiment of sorts, Schaffner said.

"You had this patient from Wuhan where the virus is, travelling to where the virus wasn't. She remained asymptomatic and infected a bunch of family members and you had a group of physicians who immediately seized on the moment and tested everyone."

According to the report by Dr Meiyun Wang of the People's Hospital of Zhengzhou University and colleagues, the woman travelled from Wuhan to Anyang on Jan. 10 and visited several relatives. When they started getting sick, doctors isolated the woman and tested her for coronavirus. Initially, the young woman tested negative for the virus, but a follow-up test was positive.

All five of her relatives developed COVID-19 pneumonia, but as of Feb. 11, the young woman still had not developed any symptoms, her chest CT remained normal and she had no fever, stomach or respiratory symptoms, such as cough or sore throat.

Scientists in the study said if the findings are replicated, "the prevention of COVID-19 infection could prove challenging."

Key questions now, Schaffner said, are how often does this kind of transmission occur and when during the asymptomatic period does a person test positive for the virus.