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

Key Who May Qualify: 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 Who Should NOT Join This Trial: 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. Always talk to your doctor about whether this trial is right for you.