Interstitial pneumonitis caused by seasonal influenza vaccine

: A 74-year-old man who received seasonal influenza vaccination at a clinic developed fever and cough the following morning. He was referred to our hospital on the 5th day after vaccination because of bilateral pulmonary infiltration shadows on a chest X-ray film. Despite the administration of sulbactam/ampicillin and roxithromycin after admission, his symptoms did not improve. His bronchoalveolar lavage fluid (BALF) obtained by bronchoscopy on the 8th hospital day revealed a CD4/CD8 ratio of 6.8, 109 x 10(4)/ml, and 39% and 16% increases in lymphocyte fractions and eosinophil levels, respectively. Transbronchial lung biopsy showed organizing pneumonia. A drug-induced lymphocyte stimulation test (DLST) for seasonal influenza vaccine with BALF showed 210% of seasonal influenza (S.I). These results indicate that this vaccine caused pneumonitis with a hypersensitive reaction, according to drug-induced lung injury criteria.