The World Health Organization recommends masks for health workers, those who are sick and caregivers of those infected, but as the virus surges, individual countries are reviewing these guidelines.
As the coronavirus outbreak approached its peak in China's Wuhan city, people across Asia scrambled to get their hands on surgical and non-surgical masks to protect themselves from the infection, causing shortages and disrupting the linear supply chain.
Countries such as South Korea and China actively encouraged people to wear masks as their cases grew.
Europeans, Middle Easterns, and Americans followed suit.
The buying and hoarding of masks continues despite the World Health Organization (WHO) and US Centers for Disease Control and Prevention (CDC) recommending it primarily as a measure for health care workers, caregivers and people with Covid-19 symptoms.
So why are many people racing to buy a face mask, is it effective, and who exactly should wear it?
"The simple answer is no one knows fully well," Dr Masood Aga, a consultant and speciality lead in occupational medicine at Sandwell and West Birmingham NHS Trust, told TRT World.
"This is partly due to the fact that some masks are not very effective in preventing catching of infection such as surgical masks, and some are effective only when they ... fit an individual [called FFP3 masks in the UK]."
Dr Aga said wearing a mask but wearing it wrong may give people a false sense of safety and increase their risk.
"Just having a mask helps people feel a bit psychologically reassured even though the risk is not decreased."
Part of a government's attempt to flatten the curve, Dr Arisina Ma, president of Hong Kong’s Public Doctors Association, told TRT World, should be "providing surgical masks and promoting universal masking amongst their citizens."
Hong Kong, which has some of the world's most dense urban environments, took a slew of measures to ensure the epidemic did not carry over from China in similar proportions.
"In a place like Hong Kong, the highest populated place in the world — and most Hong Kongers take public transportation — I advocate universal masking," Ma said.
"The people in Hong Kong took the infection seriously, we put on masks and cut down most social activity."
Wearing a mask as a way to prevent transmission is becoming commonplace in South Asia, where countries such as India and Pakistan are well on their way towards Covid-19 epidemics. But in disputed Kashmir — under a stringent lockdown since August 5 — the mask frenzy has hit hard and shortages have been reported.
"In Kashmir, we use three guidelines, each from WHO, the British Medical Journal, and Indian Council of Medical Research, and so far, all have urged healthy people to avoid wearing masks," Dr Khan Khawar Achakzai, a top internal medicine specialist at a government hospital in the region's main Srinagar city, told TRT World.
"But on the ground, things are different."
Dr Achakzai, who was quarantined recently after having come in touch with a Covid-19 patient who died later, said many doctors are advising people to wear masks.
"Because in a setting like South Asia," home to one-fourth of humanity, "wearing masks by the general public can help 'flatten the curve'."
Flattening the curve refers to community isolation and social distancing to keep the daily number of cases at a manageable level for governments and medical professionals.
"Doctors are advising it based on their local experience in these societies, where people live in joint families, in congested and tightly-knit neighbourhoods, with poor health facilities. But it's not medically recommended yet," he said.
"For spacious countries, if most social activity is already curtailed, masks are more essential for health care workers and sick people," Ma said.
Many countries take their cues from US health advisories where health officials are discussing whether to add face masks to federal guidelines for the general public.
The US is facing acute shortages of personal protective equipment or PPE including N-95 respirator masks and surgical masks.
However, the CDC is actively considering the wide use of masks outside the health care setting, which has been employed in other countries with some success, Dr Anthony Fauci, the nation's top infectious disease expert and President Donald Trump's Covid-19 adviser, was quoted by Reuters as saying.
"The thing that has inhibited that bit is to make sure that we don't take away the supply of masks from the health-care workers who need them," Fauci said.
Fauci has advised six US presidents on HIV/aids and other health issues. His presence at Trump's side is keenly monitored in the US and is seen as a reassurance that at 79, he is keeping well amid a crisis where people over 70 are most vulnerable.
Dr Angela Rasmussen, a virologist at Columbia, said in a talk organised by International Centre for Journalists on Tuesday that she is still following CDC guidelines and not wearing a mask when she leaves the house.
“Generally, it’s okay to wear a mask if we have limitless supplies, but masks alone are not the solution. They need to be coupled with other measures like physical distancing and good hygiene. The main problem is that the supply is limited, and health care workers don’t have enough masks,” Rasmussen said.
“Surgical masks generally don’t protect the wearer as much as they protect other people... That said, studies have shown that mask-wearing can reduce transmission of other viruses, including influenza. The problem is if masks are not worn correctly.”
Trump appears to be mulling adding masks to the guidance, suggesting ordinary Americans should use scarfs instead of masks so health-care workers don't face shortages.
"Use a scarf if you want ... rather than going out and getting a mask," Trump said at the White House coronavirus briefing on Tuesday.
Austria, Czech Republic and Slovakia have already made masks compulsory for the public.
Canada's British Colombia is also considering community-level use of masks. It warned on Wednesday that even if masks are included in recommendations, they should not be seen as impenetrable protection.
On Tuesday, officials of the Indian Home Ministry said they are continuing to recommend masks to only those who are sick or are caring for an infected person, but they're examining whether people need to wear homemade masks as a precaution against Covid-19.
Countries will also be looking at WHO for possible amended recommendations.
Dr Tedros Adhanom Ghebreyesus, the head of the WHO, said on Wednesday that guidelines will evolve as more is learned about the virus.
The head of WHO, however, reiterated that masks should be worn by frontline health workers, people who are sick and caregivers.
"There is no specific evidence to suggest that the wearing of masks by the mass population has any potential benefit," Dr Mike Ryan, executive director of the WHO health emergencies programme, said at a media briefing in Geneva on Monday.
"In fact, there's some evidence to suggest the opposite in the misuse of wearing a mask properly or fitting it properly."