Susceptibility and Immunity to Common Upper Respiratory Viral Infections—the Common Cold

COMMON upper respiratory viral infections, despite their frequency, have been something of an enigma to physicians and scientists in general. Little has been known about their specific etiology and the factors that influence susceptibility or resistance to infection. A prevalent view, even within recent years, has been that there is a common cold virus to which only man is susceptible, and which causes recurrent symptomatic infections without establishing immunity of the host. This concept now appears to be far too simple. Within the last decade, information has accumulated rapidly on the etiology of these common infections and the susceptibility of the host. Tis-sue culture technics have extended our knowledge of the viruses associated with respiratory illnesses. Controlled experiments with volunteers have permitted observations upon the susceptibility of man. Viruses and families of related viruses, now numbering approximately 70, have been recovered from respiratory secretions of persons suffering with respiratory illnesses of varying severity. These viruses propagated in tissue