Live attenuated influenza virus vaccines in patients with chronic broncho-pulmonary diseases. Clinical and immunological evaluation.

The safety and potency of two live attenuated influenza A virus vaccines, administered intranasally, were tested in outpatients suffering from chronic obstructive lung disease, during two successive trials performed between 1972 and 1974. The vaccine strains were representative of the prevalent influenza A virus types; the Ann strain was derived from a classical H3N2 (A/Hong-Kong/878/69) isolated and the Alice strain from a recent H3N2 drift (A/England/42/72). The serum and nasal antibody responses were studied in a total of 40 vaccinees. When a sufficient virus dose was administered, the hemagglutination-inhibition (HI) seroconversion rate was, respectively, 86 and 73% for each vaccine trial in patients with low (less than or equal to 32) prevaccination antibody titers. A booster effect was also observed in some subjects with higher prevaccination titers. In the two trials, clear-cut rises in local antibody activity, as tested in nasal washings' samples were found in, respectively, 92 and 75% of the patients devoid of initial titer before vaccination and in 40 and 37%, respectively, of the subjects having low prevaccination titers. Clinical symptoms were observed in 29% of the cases; they were, however, mild and transient and their occurrence was not necessarily related to the vaccination. Two administrations of intranasal attenuated virus appear therefore to be safe and to lead to a satisfactory antibody response in this "high risk" group of patients.