http://www.thinkexist.com Your Quotations website en-us Copyright ® ThinkExist 1999-2006 info@thinkexist.com Tue, 05 Jan 2010 00:00:00 EST "But these receptors are rare in the upper portion of the respiratory system. For the viruses to be transmitted efficiently, they have to multiply in the upper portion of the respiratory system so that they can be transmitted by coughing and sneezing." http://en.thinkexist.com/quotes/yoshiro_kawaoka/