For the findings, published in the journal Proceedings of the National Academy of Sciences, examined the chances of Covid-19 infection and how the virus is easily passed from person to person.

From trends and mitigation procedures in China, Italy and New York City, the researchers found that using a face mask reduced the number of infections by more than 78,000 in Italy from April 6-May 9 and by over 66,000 in New York City from April 17-May 9.

"Our results clearly show that airborne transmission via respiratory aerosols represents the dominant route for the spread of Covid-19," said study researcher Renyi Zhang from Texas A&M University in the US.

"By analysing the pandemic trends without face-covering using the statistical method and by projecting the trend, we calculated that over 66,000 infections were prevented by using a face mask in little over a month in New York City," Zhang added.

This inexpensive practice, in conjunction with social distancing and other procedures, is the most likely opportunity to stop the COVID-19 pandemic, the researchers said.

The study showed very clearly that using a face mask is not only useful to prevent infected coughing droplets from reaching uninfected persons but is also crucial for these uninfected persons to avoid breathing the minute atmospheric particles (aerosols).

The researchers said that many people in China have worn face masks for years, mainly because of the bad air quality of the country. "So people there are sort of used to this," he said. "Mandated face-covering helped China in containing the COVID-19 outbreak," Zhang said.

According to the team, the results should send a clear message to people worldwide -- wearing a face mask is essential in fighting the virus. "Social-distancing and washing our hands must continue, but that's not sufficient enough protection. Wearing a face mask as well as practising good hand hygiene and social distancing will greatly reduce the chances of anyone contracting the Covid-19 virus," Zhang wrote.

The researchers concluded that wearing a face mask in public corresponds to the most effective means to prevent inter-human transmission.