The team of five researchers are from the Texas A&M University, the University of Texas, the University of California, San Diego and the California Institute of Technology (Caltech).

According to the study published in the Proceedings of the National Academy of Science of the US (PNAS), the team compared the rate of Covid-19 infections in Italy and New york, both before and after the use of face masks became mandatory.

The team found that in Italy, between 6 April and 9 May, the use of face masks prevented about 78,000 infections.

Whereas in New York, between 17 April and 9 May, it prevented more than 66,000 infections.

“Wearing face masks in public corresponds to the most effective means to prevent interhuman transmission and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine and contact tracing, represents the most likely fighting opportunity to stop the Covid-19 pandemic, prior to the development of a vaccine,” wrote the researchers.

“Our results show that the airborne transmission route is highly virulent and dominant for the spread of Covid-19. Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the trends of the pandemic,” the team said.

Face masks were mandated in South Africa in early May. This ensured that every person wore a face mask when outside their homes or in a public space.

According to the Minister of Justice and Correctional services Ronald Lamola, not wearing a face mask in a public space is now treated as a criminal offence.

“It has made the lives of members of the public difficult including law enforcement officers’ lives very difficult if people are not wearing a mask in a particular place,” the minister said during a media briefing last Monday.

Lamola said that the government had taken these steps to criminalise the offence, after a large number of people had failed to wear masks in taxis and while shopping.

However, the minister has also said that “for now”, the duty of enforcing this rule is in the hands of compliance officers.

South African minister of health, Dr Zweli Mkhize, has also reiterated the use of facial masks.

"We are extremely concerned that fatigue seems to gave set in and South Africans are letting down their guard at a time when the spread of infection is surging," the minister said in a statement on Saturday.

"Masks are being abandoned or not worn properly and there is laxity setting in around frequent hand-washing. We must all appreciate that there is a direct causal link between the surge of cases and our ability, or inability, to adhere to these very basic principles," Mkhize said.

African News Agency