Evaluation of VX-828 in Healthy Participants and in Participants With Cystic Fibrosis

Key Inclusion Criteria: Parts A-D: * Participants between the ages of 18 and 55 years * Body mass index (BMI) of 18.0 to 32.0 kilogram per meter square (kg/m\^2) * A total body weight of more than (\>) 50 kg * Nonsmoker or ex-smoker for at least 3 months before screening with current nonsmoking status confirmed by urine or blood cotinine at screening * Cohort C2 only: Willing to provide a single DNA sample Part E: * Participants 18 years or older * Confirmed diagnosis of CF as determined by the investigator * A total body weight of more than or equal to (\>=) 35 kg * Participants must be heterozygous for F508del with a second CFTR allele carrying a minimal function mutation that is not responsive to ELX/TEZ/IVA therapy * Participants must have a forced expiratory volume in 1 second (FEV1) of greater than or equal to (≥) 40% of predicted normal for age, sex, and height Key Exclusion Criteria: Parts A-D: * History of febrile illness or other acute illness within 14 days before the first dose of study drug * Any condition possibly affecting drug absorption Part E: * An acute illness not related to CF (e.g., gastroenteritis) within 14 days before the first dose of study drug * History of solid organ or hematological transplantation * History of clinically significant cirrhosis with or without portal hypertension * Lung infection with organisms associated with a more rapid decline in pulmonary status Other protocol defined Inclusion/Exclusion criteria will apply.