Possible life-threatening adverse reaction to monovalent H1N1 vaccine

with no doubts regarding its benefi cial immunoprotective eff ect [1,2]. Recent reports have shown that adverse events are few and generally not life-threatening [3]. Th ere fore, a worldwide vaccination program was launched with very strong confi dence [4]. Herein, for the accumu-lative record, I report a possible life-threatening reaction of the monovalent H1N1 vaccine in Th ailand. A 38-year-old pregnant woman (gestational age of 25 weeks) was fi t and well and had regular antenatal care without any problems. She was given an H1N1 vacci nation and the following day developed diff use myalgia and minimal shortness of breath. Her condition continued to deteriorate, ultimately ending in respiratory failure on day 5 post-vaccination. On arrival at the intensive care unit, she was tachypneic, tachycardic, and hypotensive. Her chest fi lm demonstrated diff use bilateral lung infi l-tration. She was eventually intubated and ventilated with high-concentra tion oxygen and high positive end-expira-tory pressure. She was found to have bloody secretions from tracheal aspiration. Acute lung injury with pulmonary hemorrhage was, therefore, suspected. A complete physical examination revealed a severe bilateral subconjunctival hemorrhage. No other abnor-mali ties were detected. Blood labs showed a leucopenia level of 2,600/mm 3 , mild anemia with hemoglobin of 10 gm/dL, and a platelet count of 40,000/mm 3. A coagu-lation study was normal. She was also suff ering from acute renal failure with a creatinine level of 3 mg/dL. Urinalysis demonstrated proteinuria with a quantitative count of around 1.2 gm/L with microscopic hematuria. A liver function test also showed mild transaminitis. Microbiological study and culture were negative. An echocardiogram showed severe pulmonary hypertension, possibly from severe acute lung injury. Overall, she developed multiple organ failure, including acute respiratory distress syndrome (possibly from pulmonary hemorrhage), shock, acute renal failure with possible glomerulonephritis, and thrombocytopenia. Systemic autoimmune diseases, such as systemic lupus erythema tosus or systemic vasculitis, were considered in the diff erential diagnosis, but all vasculitic screens, includ ing anti-nuclear antibody, C3 and C4 levels, 50% hemolytic complement (CH 50), anti-neutrophil cytoplasmic antibody, and anti-double-stranded DNA, were negative. Th e patient's clinical condition slowly improved over the following 7 days with aggressive organ support but no specifi c management. In conclusion, the diagnosis of this patient remains unclear; however, vasculitis or an autoimmune disease is unlikely, and a severe adverse event following the H1N1 vaccination could not be completely excluded. Physicians should remain alert to possible …