Attenuated influenza virus in normal adults: role of pulmonary function studies in vaccine trials

A live attenuated virus, influenza A/Hong Kong/68(H3N2)-ts-1[E], was administered to 10 normal volunteers. Infection resulted in minor upper respiratory tract symptoms in one volunteer. An isolate from one volunteer contained a presumed revertant wild-type virus, but no clinical significance could be ascribed to this infection. Since infection with natural influenza A virus adversely affects airway dynamics, serial tests of pulmonary function were performed, including measurements of forced expiratory flow rates, lung volumes, diffusing capacity, closing volume, and total pulmonary resistance at various frequencies by the oscillometric technique. All tests performed before and on days 3, 30, and 60 after administration of virus yielded normal results throughout the study; these results suggested that there was no inflammatory response to the candidate vaccine in either the large or the small airways. Determination of total pulmonary resistance by the oscillometric technique proved to be a simple and acceptable procedure and may be useful in large-scale epidemiologic studies.