TRANSMISSION OF THE COMMON COLD TO VOLUNTEERS UNDER CONTROLLED CONDITIONS. IV. SPECIFIC IMMUNITY TO THE COMMON COLD*

Abstract

The susceptibility of volunteer subjects to an experimental common cold was determined after the initial challenge and rechallenge with the same or a different nasal secretion collected from donors with a common cold. Among 1034 subjects who received an infectious secretion as an initial challenge 449 or 42% developed colds as compared with 70 or 10% of 696 subjects who served as a control population and simultaneously received a buffer solution. Among 73 subjects who developed no cold on initial challenge, 7 or 10% developed colds on rechallenge with the same infectious secretion. Among 71 subjects who developed a cold on initial challenge, 6 or 8% developed a cold on rechallenge from 3 to 45 weeks later. The secretions had not lost their infectivity for initial volunteers. In contrast, among 74 sub-jects who developed no cold on initial challenge, 31 or 40% developed a cold when challenged later with another secretion. Among 41 subjects who developed a cold on initial challenge, 19 or 46% developed a cold when challenged with another secretion after 10 to 74 weeks. These observations suggest that the common cold is caused by a number of different viruses which are antigenically different and that following infection human subjects develop a specific immunity against the virus which lasts at least for several months.