One of the most typical questions that patients of swine flu and other healthy persons ask is “How effective are masks in prevention swine flu?” Dr Vinay Aggarwal, Internal Medicine Physician, Cedars Sinai Hospital, Los Angeles says that masks are very effective in controlling the spread of swine flu. If a person has swine flu and is in a crowded place, he/she must wear a mask because swine flu spreads through respiratory droplets that come out of the infected person by way of sneezing, coughing etc. Therefore, if an infected person wears a mask, he/she can prevent others around him/her from catching the disease.