There's new evidence to suggest that speaking and not just coughing and sneezing can spread Covid-19.
A study in the New England Journal of Medicine has found tiny droplets that come out of the mouth while speaking are infectious.
Professor of Immunology at Trinity College Dublin Luke O’Neill says the research proves everyone should be wearing a mask.
"The original idea was that you'd protect the other person from coughing. But now the fact that you can breathe the stuff out...
"You've got to wear a mask. This science supports that. We need a scientific basis for claiming things and that's why I think these studies are so good."
However, director of the National Virus Reference Laboratory, Dr Cillian De Gascun warned masks can have the effect of increasing complacency. He said: "The question is how people manage them when they're on, and whether people increase the risk of (other) people touching them, and therefore contaminating their hands and therefore contaminating surfaces.
"There's evidence to suggest when people wear masks a lot, that can increase a sense of complacency."
University of San Francisco data scientist Jeremy Howard recently led a review panel with 18 other experts from around the globe on the effectiveness of masks in warding off the virus. He said: “It actually looks a lot like (wearing masks) could be one of our most important tools."
Mr Howard cited World Health Organisation assistant director-general David Heymann’s comment that masks were equally or more effective in combating the spread of Covid-19 than social distancing, and said the situation in Taiwan provided further proof.
“The entire country of Taiwan has five deaths. Now here’s an example of a great country that is distributing masks to everybody,” Mr Howard said.
Most scientific evidence points in the same direction: keep your droplets to yourself – wear a mask.
“Our team’s review of the literature found substantial evidence in favour of widespread mask use to reduce community transmission, based on droplet dynamics, mask material analysis, efficacy studies, and behavioural studies.
“The key insight is that most discussions assume that the purpose of the mask is to protect the wearer, since this is what all doctors learn about in medical school. But actually masks work far better at blocking the infection at the source. This is called ‘source control’.”