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

Prior treatment

• History of febrile illness or other acute illness within 14 days before the first dose of study drug
• An acute illness not related to CF (e.g., gastroenteritis) within 14 days before the first dose of study drug

Other illness

• Any condition possibly affecting drug absorption
  • Part E:
• 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.

Other

• Parts A-D:

• 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