The study, published in JAMA, found that surgical masks were as effective as N95 respirators at preventing the flu, which is to say, not all that effective because, of the 446 nurses who took part in this study, nearly one in four (24%) in the surgical mask group still got the flu as did 23% of those who wore the N95 respirator. And, because both groups wore masks, it’s impossible to say how they would have fared compared with not wearing a mask at all.
Basically, there is no strong evidence to support well people wearing surgical masks in public. Or as the US Centers for Disease Control and Prevention put it: “No recommendation can be made at this time for mask use in the community by asymptomatic persons, including those at high risk for complications, to prevent exposure to influenza viruses.”
The best thing you can do to stop getting the flu is to regularly wash your hands, and try to avoid touching your face.