The main inclusion criteria include but are not limited to the following: - Has a histological diagnosis of pathological Stage I (tumor ≤4 cm) non-small cell lung cancer (NSCLC) per American Joint Committee on Cancer (AJCC) 9th Edition with at least 1of the following high-risk pathologic features as assessed locally: tumor size >2cm, visceral pleural invasion, lymphovascular invasion, or high-grade histology - Has undergone a complete surgical resection of the primary NSCLC - Has not received other prior treatment outside of definitive surgery (including but not limited to chemotherapy, immunotherapy, targeted therapy, or radiotherapy) for their current Stage I NSCLC - Has provided a tissue sample from recent surgery along with the required blood sample - Human immunodeficiency virus (HIV)-infected participants must have well-controlled HIV on antiretroviral therapy (ART) - Participants who are hepatitis B surface antigen (HBsAg) positive are eligible if they have received hepatitis B virus (HBV) antiviral therapy for at least 4 weeks, and have undetectable HBV viral load prior to randomization - Participants with history of hepatitis C virus (HCV) infection are eligible if HCV viral load is undetectable at screening

The main exclusion criteria include but are not limited to the following: - Has diagnosis of any 1 of the following: small cell lung cancer (SCLC) or, for mixed tumors, presence of small cell elements, neuroendocrine tumor with large cell components, sarcomatoid carcinoma, or two synchronous primary NSCLCs - Has any clinically significant cardiovascular disease within 12 months before randomization, including a history of coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI), valvular heart disease requiring surgical intervention, New York Heart Association Class III-IV heart failure, unstable angina, myocardial infarction (MI), pulmonary hypertension, cardiovascular accident (CVA), or hemodynamically unstable cardiac arrhythmia - HIV-infected participants with a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease - Has known additional malignancy that is progressing or has required active treatment within the past 3 years - Has active autoimmune disease that has required systemic treatment in the past 2 years. Hormonal supplementation (eg, thyroxine, insulin, or physiologic corticosteroid) is allowed - Has history of (noninfectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease - Has active infection requiring systemic therapy other than those permitted in protocol - Has history of stem cell/solid organ transplant - Participants who have not adequately recovered from major surgery or have ongoing surgical complications