The answer is no. That is not to say that masks are useless. They do help to some degree if used correctly. But the amount of protection varies with the type of mask.
What about putting handkerchief or tissue paper over your mouth and nose when someone nearby coughs and sneezes?
Again, the answer is that this too probably helps to some extent. Among masks, the N95 gives the highest level of protection, but it is still not foolproof.
Studies in healthcare institutions indicate that it provides more protection than surgical masks.
But it is difficult to wear these masks for long and other than within healthcare institutions where the risk of infection may be high, it is certainly not recommended.
Dr Shawn Vasoo, acting clinical director of the National Centre for Infectious Diseases, said a study involving more than 2,800 healthcare workers published in the Journal of the American Medical Association last year, found that N95 and surgical masks provided similar levels of protection against influenza – not the coronavirus – in an outpatient setting.
Surgical masks, if worn improperly – such as when there are gaps on the side of the face or if worn by people with beards – will let viruses through.
Dr David Carrington, a clinical virologist at St George’s, University of London, told BBC News that “routine surgical masks for the public are not an effective protection against viruses or bacteria carried in the air” because they are too loose, have no air filter and leave the eyes exposed.
A study of reusable cloth masks carried out in Vietnam involving more than 1,600 healthcare workers found that “moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection”.
In the same study published in the British Medical Journal in 2015, even some in the group wearing surgical masks got infected. These results were from healthcare workers who saw an average of 36 patients a day, over a four-week period.
The United States’ Mayo Clinic said using masks and hand sanitisers to protect against influenza is more effective than wearing masks alone. This is partly because people who wear masks may be touching them with unclean hands, for example when they want to eat or drink.
A behavioural observation study of 23 medical students at the University of New South Wales found that they touched their faces an average of 26 times an hour, and 44 per cent of the times that they touched their faces involved contact with mucous membrane including in the eyes and nose.
Another problem with surgical masks is the longer you wear one, the less effective it becomes, especially if it gets damp from your breath.
So wearing masks may give a false sense of security, and people may become lax about taking other protective steps, such as washing their hands frequently.
Wearing masks may give a false sense of security, and people may become lax about taking other protective steps, such as washing their hands frequently.