Breakthrough Infection/positive SARS-CoV-2 testing via nasopharyngeal PCR/COVID-19 pneumonia; Breakthrough Infection/positive SARS-CoV-2 testing via nasopharyngeal PCR/COVID-19 pneumonia; This is a literature report.  A patient (no qualifiers provided) received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE) (Batch/Lot number: unknown) as dose 2, single and (Batch/Lot number: unknown) as dose 1 single for COVID-19 immunisation. Relevant medical history included: "Hematologic Malignancies" (ongoing). The patient's concomitant medications were not reported. The following information was reported: DRUG INEFFECTIVE (medically significant), outcome "unknown", described as "Breakthrough Infection"; COVID-19 (medically significant), outcome "unknown", described as "COVID-19". The patient underwent the following laboratory tests and procedures: sars-cov-2 antibody test: positive.  Follow-up (25Jan2022):This is a literature report. Updated information: Patient's demographic information, relevant medical history, lab data, suspect vaccination date, clinical course were updated.  Authors' second patient is a 68-year-old male with treatment-related B-cell ALL (acute lymphocytic leukaemia) who was treated with dexamethasone, vincristine, methotrexate, doxorubicin, and pegasparaginase, and subsequently underwent a matched unrelated donor allogeneic stem cell transplantation in 2019. His transplant course was complicated by multiple infections, graft versus host disease (GVHD) requiring extracorporeal photopheresis (ECP), tacrolimus, sirolimus, and ruxolitinib. He ultimately developed relapsed extramedullary ALL in the left femur two years later, on 15Apr2021. He received the Spikeprotein-encoding Pfizer/BioNTech mRNA COVID-19 vaccination series (BNT162b2,BioNTech/Pfizer) in April 2021. In anticipation of receiving therapy in Jul2021, his screening process revealed positive SARS-CoV-2 testing via nasopharyngeal PCR and a negative nucleocapsid COVID-19 IgG. His vital signs and review of systems were otherwise unremarkable. In the setting of recent vaccination, it was felt that he had an asymptomatic infection. The decision was made to proceed with chemotherapy, and the patient was discharged three days later. The patient then presented with low-grade fevers, fatigue, and exertional dyspnea one-week post-discharge. His physical exam was noteworthy for tachycardia and hypoxia with an oxygen saturation of 89%. A comprehensive nasopharyngeal respiratory viral panel (RVP) was obtained and was positive for SARS-CoV-2 by PCR. Computed tomography of the chest revealed bilateral peripherally distributed ground-glass and consolidative opacities within the lower lung zones. He was admitted to the hospital for management of his COVID-19 pneumonia. He was initiated on dexamethasone 6 mg daily, remdesivir, enoxaparin prophylaxis, and supplemental oxygen to maintain a saturation above 92%. After five days of hospitalization, the patient improved clinically and was then discharged with home oxygen to complete a full ten days of dexamethasone therapy. His COVID-19 IgG (spike), semi-quantitative antibodies that were obtained on admission eventually returned as undetectable.  No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.; Sender's Comments: The efficacy of a drug varies from one patient to another and can be affected by different factors; however, a contributory role of BNT162B2 to the reported event Drug ineffective and COVID-19 cannot be ruled out based on the limited information provided.,Linked Report(s) : US-PFIZER_INC-202200063709 Same article/ drug/event and different patient