evidence: But health experts say the evidence is clear that masks can help prevent the spread of COVID-19 and that the more people wearing masks, the better. [...] Two compelling case reports also suggest that masks can prevent transmission in high-risk scenarios, said Chin-Hong and Rutherford. In one case, a man flew from China to Toronto and subsequently tested positive for COVID-19. He had a dry cough and wore a mask on the flight, and all 25 people closest to him on the flight tested negative for COVID-19. In another case, in late May, two hair stylists in Missouri had close contact with 140 clients while sick with COVID-19. Everyone wore a mask and none of the clients tested positive. [...] Another factor to remember, noted Rutherford, is that you could still catch the virus through the membranes in your eyes, a risk that masking does not eliminate.