US suspends military training with Pakistan says report

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 31: The United States has performed over one million coronavirus tests so far, said President Donald Trump on Monday.

"Today, we reached a historic milestone in our war against coronavirus. Over 1 million Americans have now been tested, more than any other country by far, not even close," Trump said during a press briefing.

US Health Secretary Alex Azar said that approximately 100,000 samples are tested for coronavirus daily.

The number of novel coronavirus (COVID-19) cases within the United States surpassed 150,000 and the death toll has reached 2828, according to Johns Hopkins University. 

Washington, May 27: Most viruses and other germs do not spread easily on flights, the US Center for Disease Control and Prevention has said in its COVID-19 guidelines which do not recommend following social distancing between two passengers inside a plane or keeping the middle seat unoccupied.

As a result of coronavirus pandemic, air traffic inside the US has come to a near halt. Air traffic is said to be down to about 90 per cent. For all travellers coming from overseas, the Center for Disease Control and Prevention (CDC) has recommended 14 days quarantine.

"Most viruses and other germs do not spread easily on flights because of how air circulates and is filtered on aeroplanes," the CDC has said in its set of COVID-19 guidelines for air travellers.

However, it noted that the air travellers were not risk-free especially in the time of the coronavirus pandemic and recommended Americans to avoid travel as far as possible.

"Air travel requires spending time in security lines and airport terminals, which can bring you in close contact with other people and frequently touched surfaces," it said.

"Social distancing is difficult on crowded flights, and you may have to sit near others (within six feet), sometimes for hours. This may increase your risk for exposure to the virus that causes COVID-19," the CDC said.

But instead of recommended social distancing inside commercial planes, the CDC has advised a series of preventive and hygienic measures to be taken by the airlines pilot and crew to prevent the spread of coronavirus.

The US Department of Transportation and Federal Aviation Administration in its latest safety alerts for operators on May 11 said that air carriers and crews conducting flight operations having a nexus to the US, including both domestic and foreign air carriers, should follow CDC's occupational health and safety guidance.

The CDC issued its guidelines in first guidelines for the airlines and airline crew on March and again in May.

The CDC, which has issued an exhaustive social guideline measures in various sections, is silent on keeping the middle seat of a plane unoccupied so as to maintain the six feet distance between two passengers.

It calls for the plane crew to report to the CDC a traveller with specific COVID-19 symptoms like fever, persistent cough, difficulty in breathing and appearing unwell.

Asking the airlines and cabin crew to review infection control guidelines for cabin crew, the CDC recommends several measures for cabin crew to protect themselves and others, manage a sick traveller, clean contaminated areas, and take actions after a flight.

Prominent among them include washing hands often with soap and water for at least 20 seconds, particularly after assisting sick travellers or touching potentially contaminated body fluids or surfaces and use of alcohol-based hand sanitizer (containing at least 60 per cent alcohol) if soap and water are not available.

Airlines should consider providing alcohol-based hand sanitizer to cabin and flight crews for their personal use, it said.

The CDC guidelines do not recommend following social distancing inside a plane between two passengers or keeping the middle seat unoccupied. But it asks to minimise contact between passengers and cabin crew and the sick person.

"If possible, separate the sick person from others (by a distance of 2 meters or 6 feet, ideally) and designate one crew member to serve the sick person. Offer a facemask, if available and if the sick person can tolerate it. If a facemask is not available or cannot be tolerated, ask the sick person to cover their mouth and nose with tissues when coughing or sneezing," said the CDC guidelines.

If no symptomatic passengers were identified during or immediately after the flight, the CDC recommends airlines to follow routine operating procedures for cleaning aircraft, managing solid waste, and wearing PPE.

"If symptomatic passengers are identified during or immediately after the flight, routine cleaning procedures should be followed, and enhanced cleaning procedures should also be used," it said.

Clean porous (soft) surfaces (e.g, cloth seats, cloth seat belts) at the seat of the symptomatic passengers and within 6 feet of the symptomatic passengers in all directions, it added.