Patient description: The patients is a 25-year-old G1 P1 pregnant woman who is 24W3D gestational old who developed a sudden unset of fever and chills, accompany with nausea and vomiting. She also complains of dysuria, urgency and frequency. She also reports some severe pain in the flank. Her vital signs are: T = 39.7ºC, P = 117, R = 20, and BP = 113/74 mm Hg. Physical examination reveals tenderness on palpation of both costovertebral angles. She has no history of recurrent UTI prior to her pregnancy or any other underlying disease. The urine culture showed Gram-negative rod-shaped bacterial cells, leukocytes, and leukocyte casts. The blood culture is negative. A CBC shows Hb 12.9 g/dL, Hct 39%, MCV 76 fL, WBC count 14,120/µL.

Clinical trial eligibility criteria: eligible ages (years): 18.0-65.0,  Sickle Cell Disease Part B Only The participant must have uncomplicated acute VOC (no significant organ dysfunction [Alanine aminotransferase (ALT) >3x upper limit of normal (ULN) of local lab; creatinine greater than (>) 2 milligram per deciliter (mg/dL); symptomatic cardiac decompensation, new neurologic symptoms] or signs or symptoms of systemic infection, or fever with body temperature of greater than or equal to (>=) 38.5 degree celsius(ºC)] The participant requires hospitalization and parenteral narcotic treatment The participant must be able to receive the first IP dose within 24 hours after first administration of the IV narcotic dose Outpatient healthcare facility treatment, if any, for the same VOC episode has occurred no greater than 48 hours prior to screening. Part A and B Age 18 to 65 years at the time of signing the informed consent An understanding, ability, and willingness to fully comply with study procedures and requirements Ability to voluntarily provide written, signed, and dated (personally or via a legally authorized representative) informed consent to participate in the study Male or female with a documented history of HbSS or HbSβo thalassemia (based on clinical record of genetic, electrophoresis, or high-performance liquid chromatography testing) Participant currently taking hydroxyurea must be on a stable dosing for 3 months at screening  Part A only: -The participant was diagnosed with acute VOC in last 21 days, at screening visit. Part B only: -The participant has experienced > = 6 episodes of acute VOC in last 180 days, at Screening Visit. Parts A and B The participant has undergone blood transfusion within the last 30 days or blood transfusion on >=2 occasions in the last 90 days, at Screening visit The participant has a history of acquired or congenital thrombotic thrombocytopenic purpura The participant has serum creatinine level greater than(>)1.2 milligrams per deciliter (mg/dL) The participant has alanine transaminase >3×upper limit of normal (based on clinical laboratory normal range) The participant has a hemoglobin level <5 grams per deciliter (g/dL) The participant has a platelet count of <100 000/cubic millimeter (mm3) Minor infection that does not meet the following uncomplicated urinary tract infection with body temperature <38.5°C [101.3°F] and no costovertebral angle tenderness; or uncomplicated otitis media; or uncomplicated streptococcal pharyngitis The participant has fever with body temperature of >= 38.5ºC (101.3ºF) and one of the following 1. The participant has positive finding (suspicious for infection) on diagnostic tests, such as cerebral spinal fluid evaluation, radiographic evidence of pulmonary infiltrate, or bacterial culture of normally sterile sites. 2. The participant has examination findings leading to diagnosed or strongly suspected bone or joint infection. 3. There has been a determination by the participant's physician that bacterial or serious systemic viral infection is likely (example (eg), influenza, mononucleosis) The participant has Acute Chest Syndrome (ACS), diagnosed or strongly suspected, as evidenced by a new infiltrate on chest radiograph, and one or more of the following 1. Fever with body temperature >39°C (102.2°F) 2. Hypoxia (confirmed by arterial blood gases with partial pressure of arterial oxygen (PaO2) <70 millimeter of mercury (mmHg)) 3. Chest pain 4. Suspicious findings on physical examination (tachypnea, intercostal retraction,wheezing, and/or rales)