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Global coronavirus infections passed 14 million on Friday, according to a Reuters tally, marking the first time there has been a surge of 1 million cases in under 100 hours.

The first case was reported in China in early January and it took three months to reach 1 million cases. It has taken just four days to climb to 14 million cases from 13 millionrecorded on July 13.

The United States, with more than 3.6 million confirmed cases, is still seeing huge daily jumps in its first wave of Covid-19 infections. The United States reported a daily global record of more than 77,000 new infections on Thursday, while Sweden has reported 77,281 total cases since the pandemic began.

Despite the surging cases, a cultural divide is growing in the country over wearing masks to slow the spread of the virus, a precaution routinely taken in many other nations.

U.S. President Donald Trump and his followers have resisted a full-throated endorsement of masks and have been calling for a return to normal economic activity and reopening schools despite the surging cases.

COVID-19 Pandemic Tracker: 15 countries with the highest number of coronavirus cases, deaths

Other hard-hit countries have “flattened the curve” and are easing lockdowns put in place to slow the spread of the novel virus while others, such as the cities of Barcelona and Melbourne, are implementing a second round of local shutdowns.

The number of cases globally is around triple that of severe influenza illnesses recorded annually, according to the World Health Organization.

The pandemic has now killed more than 590,000 people in almost seven months, edging towards the upper range of yearly influenza deaths reported worldwide. The first death was reported on Jan. 10 in Wuhan, China before infections and fatalities then surged in Europe and later in the United States.

The Reuters tally, which is based on government reports, shows the disease is accelerating the fastest in the Americas, which account for more than half the world’s infections and half its deaths.
In Brazil, more than 2 million people have tested positive including President Jair Bolsonaro, and more than 76,000 people have died.

India, the only other country with more than 1 millioncases, has been grappling with an average of almost 30,000 new infections each day for the last week.

Those countries were the main drivers behind the World Health Organization on Friday reporting a record one-day increase in global coronavirus cases of 237,743.

In countries with limited testing capacity, case numbers reflect only a proportion of total infections. Experts say official data likely under-represents both infections and deaths.

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.