Since its release in August 2020, the Guidebook "How to prevent infection" has focused on the main theme of "awareness of and caution against airborne transmission" of the new coronaviruses, SARS-CoV-2 and has proposed specific infection prevention methods.　In the meantime, WHO, CDC, and then in Japan, the Ministry of Health, Labour and Welfare have become officially accepting "airborne transmission" of novel coronaviruses as the main route. However, the emphasis on droplet and contact transmission rather than airborne transmission remains the mainstream in actual method for preventing infection and has remained incompletely adequate as an infection control measure to the present day.　In validating the mechanism of airborne infection based on Mikawa-Kase-AQIP simulation model, the primary route of transmission for SARS-CoV-2 and for influenza, colds, and other respiratory infections as well has shown clearly. Therefore, since this guidebook is applicable to all respiratory infections, the title has been changed to "Guidebook for How to Prevent Respiratory Infectious Diseases" 15th edition.