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London/Milan, Jun 2: World Health Organization experts and a range of other scientists said on Monday there was no evidence to support an assertion by a high profile Italian doctor that the coronavirus causing the COVID-19 pandemic has been losing potency.

Professor Alberto Zangrillo, head of intensive care at Italy's San Raffaele Hospital in Lombardy, which bore the brunt of Italy's COVID-19 epidemic, on Sunday told state television that the new coronavirus "clinically no longer exists".

But WHO epidemiologist Maria Van Kerkhove, as well as several other experts on viruses and infectious diseases, said Zangrillo's comments were not supported by scientific evidence.

There is no data to show the new coronavirus is changing significantly, either in its form of transmission or in the severity of the disease it causes, they said.

"In terms of transmissibility, that has not changed, in terms of severity, that has not changed," Van Kerkhove told reporters.

It is not unusual for viruses to mutate and adapt as they spread, and the debate on Monday highlights how scientists are monitoring and tracking the new virus. The COVID-19 pandemic has so far killed more than 370,000 people and infected more than 6 million.

Martin Hibberd, a professor of emerging infectious disease at the London School of Hygiene & Tropical Medicine, said major studies looking at genetic changes in the SARS-CoV-2 virus that causes COVID-19 did not support the idea that it was becoming less potent, or weakening in any way.

"With data from more than 35,000 whole virus genomes, there is currently no evidence that there is any significant difference relating to severity," he said in an emailed comment.

Zangrillo, well known in Italy as the personal doctor of former Prime Minister Silvio Berlusconi, said his comments were backed up by a study conducted by a fellow scientist, Massimo Clementi, which Zangrillo said would be published next week.

Zangrillo told Reuters: "We have never said that the virus has changed, we said that the interaction between the virus and the host has definitely changed."

He said this could be due either to different characteristics of the virus, which he said they had not yet identified, or different characteristics in those infected.

The study by Clementi, who is director of the microbiology and virology laboratory of San Raffaele, compared virus samples from COVID-19 patients at the Milan-based hospital in March with samples from patients with the disease in May.

"The result was unambiguous: an extremely significant difference between the viral load of patients admitted in March compared to" those admitted last month, Zangrillo said.

Oscar MacLean, an expert at the University of Glasgow's Centre for Virus Research, said suggestions that the virus was weakening were "not supported by anything in the scientific literature and also seem fairly implausible on genetic grounds."

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.

Apr 9: The UAE Cabinet, chaired by His Highness Sheikh Mohammed bin Rashid Al Maktoum, Vice President and Prime Minister of the UAE and Ruler of Dubai, adopted a resolution to grant paid leave to select categories of employees at the federal government.

This move is part of a series of precautionary measures and procedures taken by the UAE government to bring the Covid-19 pandemic under control.

The resolution stipulates that married employees of the federal government may take fully paid leave to take care of their children below the age of 16. The age condition shall not apply to people of determination, as well as in cases where a spouse is subject to self-isolation or quarantine that requires no contact with family members, upon a decision from the Ministry of Health and Prevention.

The resolution also applies to employees whose spouses work in vital health-related occupations, such as doctors, nurses, paramedics and other medical jobs that require exposure to infected people, as well as employees of quarantine centres, throughout the emergency period witnessed by the country.

Pursuant to the resolution, the relevant ministry or federal authority may ask employees holding essential technical occupations to work remotely instead of taking leave.

The resolution was issued in line with the UAE government's keenness to support employees and provide them with a safe and healthy working environment, as well as to protect the health and safety of government employees and their families, during the current crisis that requires greater efforts, additional working hours, and in some cases, exposure to infected people.