Data of 267 million Facebook users leaked online

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, Jul 7: President Donald Trump on Tuesday formally started the withdrawal of the United States from the World Health Organization, making good on threats to deprive the UN body of its top funding source over its response to the coronavirus.

Public health advocates and Trump's political opponents voiced outrage at the departure from the Geneva-based body, which leads the global fight on maladies from polio to measles to mental health -- as well as Covid-19, at a time when cases have again been rising around the world.

After threatening to suspend the $400 million (Dh1.47 billion) in annual US contributions and then announcing a withdrawal, the Trump administration has formally sent a notice to UN Secretary-General Antonio Guterres, a State Department spokesperson said.

The withdrawal is effective in one year -- July 6, 2021 -- and Joe Biden, Trump's presumptive Democratic opponent, is virtually certain to stop it and stay in the WHO if he wins the November election.

A spokesman for Guterres and the global health body itself confirmed that the United States, a key founding WHO member, gave its notice.

In a speech earlier in the day, WHO chief Tedros Adhanom Ghebreyesus said of Covid-19, "National unity and global solidarity are more important than ever to defeat a common enemy."

In line with conditions set when the WHO was set up in 1948, the United States can leave within one year but must meet its remaining assessed financial obligations, the UN spokesman said.

'Total control'

In late May, Trump said that China exerted "total control" over the WHO and accused the UN body led by Tedros, an Ethiopian doctor and diplomat, of failing to implement reforms.

Blaming China for the coronavirus, Trump, a frequent critic of the UN, said the United States would redirect funding "to other worldwide and deserving, urgent, global public health needs."

Democratic lawmakers have accused Trump of seeking to deflect criticism from his handling of the pandemic in the United States, which has suffered by far the highest death toll of any nation despite the president's stated hope that the virus will disappear.

"To call Trump's response to Covid chaotic and incoherent doesn't do it justice," said Senator Robert Menendez, the top Democrat on the Foreign Relations Committee.

"This won't protect American lives or interests -- it leaves Americans sick and America alone," he wrote on Twitter.

Representative Ami Bera, himself a physician, said that the United States and World Health Organization had worked "hand in hand" to eradicate smallpox and nearly defeat polio.

"Our cases are increasing," Bera said of Covid-19. "If the WHO is to blame: why has the US been left behind while many countries from South Korea to New Zealand to Vietnam to Germany return to normal?"

Even some of Trump's Republican allies had voiced hope that he was exerting pressure rather than making a final decision to abandon the World Health Organization.

The investigative news outlet ProPublica reported last month that most of Trump's aides were blindsided by the WHO withdrawal announcement, which he made during an appearance about China. 

The Trump administration has said that the WHO ignored early signs of human-to-human transmission in China, including warnings from Taiwan -- which, due to Beijing's pressure, is not part of the UN body.

While many public health advocates share some criticism of the WHO, they question what other options the world body had other than to work with China, where Covid-19 was first detected late last year in the city of Wuhan.

The anti-poverty campaign ONE said the United States should work to reform, not abandon, the WHO.

"Withdrawing from the World Health Organization amidst an unprecedented global pandemic is an astounding action that puts the safety of all Americans the world at risk," it said.

Wuhan, Apr 15: In the six days after top Chinese officials secretly determined they likely were facing a pandemic from a new coronavirus, the city of Wuhan at the epicenter of the disease hosted a mass banquet for tens of thousands of people; millions began traveling through for Lunar New Year celebrations.

President Xi Jinping warned the public on the seventh day, Janaury 20. But by that time, more than 3,000 people had been infected during almost a week of public silence, according to internal documents obtained by The Associated Press and expert estimates based on retrospective infection data.

That delay from Jan 14 to Jan. 20 was neither the first mistake made by Chinese officials at all levels in confronting the outbreak, nor the longest lag, as governments around the world have dragged their feet for weeks and even months in addressing the virus.

But the delay by the first country to face the new coronavirus came at a critical time — the beginning of the outbreak. China's attempt to walk a line between alerting the public and avoiding panic set the stage for a pandemic that has infected almost 2 million people and taken more than 126,000 lives.

A This is tremendous, a said Zuo-Feng Zhang, an epidemiologist at the University of California, Los Angeles. If they took action six days earlier, there would have been much fewer patients and medical facilities would have been sufficient. We might have avoided the collapse of Wuhan's medical system.

Other experts noted that the Chinese government may have waited on warning the public to stave off hysteria, and that it did act quickly in private during that time.

But the six-day delay by China's leaders in Beijing came on top of almost two weeks during which the national Center for Disease Control did not register any cases from local officials, internal bulletins obtained by the AP confirm. Yet during that time, from Jan 5 to Jan 17, hundreds of patients were appearing in hospitals not just in Wuhan but across the country.

It's uncertain whether it was local officials who failed to report cases or national officials who failed to record them. It's also not clear exactly what officials knew at the time in Wuhan, which only opened back up last week with restrictions after its quarantine.

But what is clear, experts say, is that China's rigid controls on information, bureaucratic hurdles and a reluctance to send bad news up the chain of command muffled early warnings. The punishment of eight doctors for rumor-mongering, broadcast on national television on Jan. 2, sent a chill through the city's hospitals.

Doctors in Wuhan were afraid, said Dali Yang, a professor of Chinese politics at the University of Chicago. It was truly intimidation of an entire profession. Without these internal reports, it took the first case outside China, in Thailand on Jan 13, to galvanize leaders in Beijing into recognising the possible pandemic before them. It was only then that they launched a nationwide plan to find cases distributing CDC-sanctioned test kits, easing the criteria for confirming cases and ordering health officials to screen patients, all without telling the public.

The Chinese government has repeatedly denied suppressing information in the early days, saying it immediately reported the outbreak to the World Health Organization.

Allegations of a cover-up or lack of transparency in China are groundless, said foreign ministry spokesman Zhao Lijian at a Thursday press conference.

The documents show that the head of China's National Health Commission, Ma Xiaowei, laid out a grim assessment of the situation on Jan. 14 in a confidential teleconference with provincial health officials.

A memo states that the teleconference was held to convey instructions on the coronavirus from President Xi Jinping, Premier Li Keqiang and Vice Premier Sun Chunlan, but does not specify what those instructions were.

The epidemic situation is still severe and complex, the most severe challenge since SARS in 2003, and is likely to develop into a major public health event, the memo cites Ma as saying.

The National Health Commission is the top medical agency in the country. In a faxed statement, the Commission said it had organised the teleconference because of the case reported in Thailand and the possibility of the virus spreading during New Year travel. It added that China had published information on the outbreak in an open, transparent, responsible and timely manner," in accordance with important instructions repeatedly issued by President Xi.

The documents come from an anonymous source in the medical field who did not want to be named for fear of retribution. The AP confirmed the contents with two other sources in public health familiar with the teleconference. Some of the memo's contents also appeared in a public notice about the teleconference, stripped of key details and published in February.

Under a section titled sober understanding of the situation, the memo said that clustered cases suggest that human-to-human transmission is possible. It singled out the case in Thailand, saying that the situation had changed significantly because of the possible spread of the virus abroad.

With the coming of the Spring Festival, many people will be traveling, and the risk of transmission and spread is high, the memo continued.