Initial literature report received on 24 Jan 2011: This article described about vaccine-failure in a pregnant woman with 2009 H1N1. This pregnant patient was vaccinated with H1N1 (manufacturer and batch number unknown) in Nov 2009 at 25 weeks of gestation. In Feb 2010 at 37 weeks of gestation, she developed a dry cough and headache, for which she was seen by her obstetrician and she was prescribed amoxicillin. After two days, she presented to the emergency with spontaneous rupture of membranes. She was followed for prenatal care and diagnosed with mild pregnancy-induced hypertension, for which she was not treated. On the same day, she underwent a Caesarean delivery due to failure to labour progress and required general anaesthesia because of an elevated partial prothrombin time of unknown cause (partial thromboplastin time was 39.5) and concerned for bleeding complications with an epidural. The delivery and anaesthesia course were uncomplicated. A newborn did well. Several hours after extubation following caesarean delivery, the patient became progressively hypoxic with a fever of 38.9 degree Celsius. Her physical examination was remarkable for a heart rate of 124 beats per minute, blood pressure of 132/77 mm Hg and oxygen saturation of 93% on 5 L oxygen by nasal cannula. She was noted to be in moderate respiratory distress with bilateral rales on lung auscultation. Her complete blood cell count showed a hematocrit of 32.5%, a platelet count of 147 x 10^9/L and a white blood cell count of 11.2 x 10^9/L with a differential of 86% neutrophils, 7% lymphocytes and 7% monocytes. Chemistry results were normal. A chest radiograph revealed bilateral infiltrates and a chest computed tomography showed diffuse, bilateral pneumonitis. Results of chest X-ray and chest CT scan were consistent with acute respiratory distress syndrome. She was immediately transferred to the intensive care unit for respiratory failure and sepsis, possibly due to aspiration pneumonia or amniotic fluid embolism. In intensive care, she required mechanical ventilation and was started on broad-spectrum antibiotics and high-dose steroids. A respiratory specimen tested positive for 2009 H1N1 by polymerase chain reaction. She was started on oseltamivir at 75 mg every 12 hours. Microbiologic testing for bacteria was negative including urine, blood and sputum cultures. She subsequently improved and was extubated on hospital day 11 and discharged home after 3 days. Testing of paired sera collected 2 days before symptom onset (obtained as part of a routine blood draw) and 11 days after symptom onset (during hospitalization) was performed which revealed the acute serum was negative for antibody to both the 2009 H1N1 and seasonal influenza strain A/Brisbana/59/07 by hemagglutination inhibition (HI) and microneutralization (MN) assays whereas the convalescent serum was positive for antibody to the 2009 H1N1 (HI=1:1640, MN=1:320) but negative for A/Brisbane/59/07. The author commented that clinicians should remain   [Due to memory limitations, the remainder of this text could not be compared.]  n vigilant for 2009 H1N1 infection in pregnant women and should not delay initiation of antiviral treatment of women with suspected 2009 H1N1 infection, regardless or rapid test result or vaccination status