COVID-19: Record 4,591 Americans die in last 24 hours

Los Angeles, Apr 30: Los Angeles will begin offering coronavirus">coronavirus testing for free to all citizens regardless of whether they have symptoms, Mayor Eric Garcetti said on Wednesday, adding that LA is the first major US city to take such an initiative.

During the press conference, Garcetti announced that all county residents can now get free coronavirus">coronavirus testing. 

He said the announcement will only apply to city residents for now, but that a similar plan is in development for Los Angeles County,
Garcetti also took to Twitter to announce the same. "Announcing that L.A. is now the first major city in America to offer free COVID-19 testing to all residents. 

While priority will still be given to those with symptoms, individuals without symptoms can also be tested. Sign up at Coronavirus.LACity.org/Testing," he said
Under the new guidelines, priority for the same- or next-day testing will still be given to people with symptoms, such as a fever, cough, and shortness of breath. The free testing will also be prioritized for certain critical frontline workers who interact with the public.

Until now, only residents with symptoms as well as essential workers and those in institutional settings like nursing homes could be tested.

On Wednesday, the LA County reported 1,541 new cases, bringing the total to 22,485 - a seven per cent increase since yesterday.

This includes a backlog of cases that were processed. In the city, there were 683 new cases on Wednesday, bringing the total to 10,380 -- a 7 percent increase since yesterday.

Apr 26: The Chinese city of Wuhan, where the global coronavirus pandemic began, now has no remaining cases in its hospitals, a health official told reporters on Sunday.

"The latest news is that by April 26, the number of new coronavirus patients in Wuhan was at zero, thanks to the joint efforts of Wuhan and medical staff from around the country," National Health Commission spokesman Mi Feng said at a briefing.

The city had reported 46,452 cases, 56% of the national total. It saw 3,869 fatalities, or 84% of China's total.

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.