A Study to Investigate Safety, Tolerability, and Pharmacokinetics of Oral AZD0233 Compared With Placebo in Healthy Adult Participants.

Inclusion Criteria: * Healthy male and/or female participants with suitable veins for cannulation or repeated venipuncture. * All females must have a negative pregnancy test at the Screening Visit and on admission to the Clinical Unit. * Females of non-childbearing potential must be confirmed at the Screening Visit by fulfilling one of the following criteria: 1. Post-menopausal defined as amenorrhea for at least 12 months following cessation of all exogenous hormonal treatments and follicle-stimulating hormone (FSH) levels in the post-menopausal range. 2. Documentation of irreversible surgical sterilization by hysterectomy, bilateral oophorectomy, or bilateral salpingectomy but not tubal ligation. * Sexually active fertile male participants with partners of childbearing potential must adhere to the specified contraception methods from the time of first administration of study intervention until 3 months after the study Follow-up Visit. * Have a body mass index between 18 and 30 kg/m² inclusive and weigh at least 50 kg. Note: For Japanese sub-Cohort minimum weight of 45 kg is acceptable. • For the healthy Japanese sub-Cohorts: healthy Japanese participants (e.g., natives of Japan or Japanese Americans) are defined as having both parents and 4 grandparents who are Japanese. This includes healthy second and third generation participants of Japanese descent whose parents or grandparents are living in a country other than Japan. Exclusion Criteria: * History of any clinically important disease or disorder which may either put the participant at risk because of participation in the study or influence the results or the participant's ability to participate in the study. * History or presence of gastrointestinal, hepatic, or renal disease or any other condition known to interfere with absorption, distribution, metabolism, or excretion of drugs. * Any clinically important illness, medical/surgical procedure, or trauma within 4 weeks of the first administration of study intervention. * Any clinically important abnormalities in clinical chemistry, hematology, urinalysis, laboratory values or vital signs at Screening and/or first admission to the Clinical Unit. * Any clinically important abnormalities in rhythm, conduction or morphology of the resting electrocardiogram (ECG) and any clinically important abnormalities in the 12-lead ECG that may interfere with the interpretation of corrected QT (QTc) interval changes in heart rate. * Current smokers or those who have smoked or used nicotine products (including e-cigarettes) within the previous 3 months prior to Screening. * Known or suspected history of alcohol or drug abuse or excessive intake of alcohol. * Positive screen for drugs of abuse, or alcohol or cotinine at Screening or on each admission to the Clinical Unit. * History of severe allergy/hypersensitivity or ongoing clinically important allergy/hypersensitivity, or history of hypersensitivity to drugs of a similar class to AZD0233. * Use of drugs with enzyme \[Cytochrome P450 3A (CYP3A)\]/ transporter \[breast cancer resistance protein (BCRP) and organic anion transporting polypeptide 1B (OATP1B)\] inducing/ inhibiting properties such as St John's Wort within 3 weeks prior to the first administration of study intervention. * Use of any prescribed or nonprescribed medication including antacids, analgesics (other than paracetamol/acetaminophen), herbal remedies, mega dose vitamins (intake of 20 to 600 times the recommended daily dose) and minerals during the 2 weeks prior to the first administration of study intervention or longer if the medication has a long half-life. Hormone replacement therapy medications are allowed for female participants. * Has received another new chemical entity (defined as a compound which has not been approved for marketing) within 30 days or 5 half-lives (whichever is longest) of the first administration of investigational medicinal product (IMP) in this study. The period of exclusion begins one month after the final dose. * Participants who have previously received AZD0233. * Active systemic bacterial, viral, or fungal infection within 14 days prior to dosing or presence of fever (confirmed tympanic body temperature \> 37.6 °C) within 14 days prior to dosing on Day 1 depending on experienced symptoms. * Clinically significant serious active and chronic infections within 60 days prior to randomization. * Known history of primary immunodeficiency (congenital or acquired) or an underlying condition that predisposes to infection. * Concomitant immunosuppressive and/or steroid treatment. * Any positive result on Screening for serum hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), hepatitis C antibody, human immunodeficiency virus (HIV). * Clinical signs and symptoms consistent with COVID-19. * Participants who are vegans or have medical dietary restrictions. * Involvement in the planning and/or conduct of the study (applies to both AstraZeneca staff and/or staff at the Clinical Unit). * Judgment by the investigator that the participant should not participate in the study if they have any ongoing or recent (ie, during the Screening period) minor medical complaints that may interfere with the interpretation of study data or are considered unlikely to comply with study procedures, restrictions, and requirements. * Participants who cannot communicate reliably with the investigator. * Vulnerable participants, e.g., kept in detention, protected adults under guardianship, trusteeship, or committed to an institution by governmental or juridical order.