['influenza a']
['vx-787 300 mg', 'vx-787 600 mg', 'oseltamivir 75 mg', 'placebo']

        Inclusion Criteria: Part A

          1. Willing and able to comply with the NP swab procedure

          2. Subject will sign and date an informed consent form (ICF)

          3. Presenting to the clinic with symptoms suggestive of a diagnosis of acute influenza.
             Symptoms include oral temperature ≥38°C (100.4°F) within the prior 24 hours, at least
             1 respiratory symptom AND at least 1 systemic symptom.

          4. Understand that no study treatment will be provided to subjects in Part A but that
             they are free to receive any treatment considered appropriate by their physician

        Part B

          1. Willing and able to comply with study requirements including treatment plan, study
             restrictions, laboratory tests, contraceptive guidelines, and other study procedures

          2. Subject will sign and date an ICF

          3. Present to the clinic with symptoms suggestive of a diagnosis of acute influenza.
             Symptoms include documented oral temperature ≥38°C (100.4°F) any time during the
             screening process, at least 1 respiratory symptom AND at least 1 systemic symptom,
             both scored as at least "moderate".

          4. The time of onset of flu-like symptoms to the time anticipated for the start of
             treatment must be ≤48 hours. Onset of symptoms is defined as the first time (within 1
             hour) the subject becomes aware of respiratory or systemic symptoms compatible with
             the flu or experiences an oral temperature ≥38°C (100.4°F)

          5. Positive Rapid Influenza Diagnostic Test for influenza type A

          6. Body mass index (BMI) of 18.0 to 33.0 kg/m2, inclusive, and a total body weight >50 kg

        Exclusion Criteria: Part B

          1. History of any illness or any clinical condition that, in the opinion of the
             investigator or the subject's general practitioner, might confound the results of the
             study or pose an additional risk in administering study drug(s) to the subject.

          2. Any condition possibly affecting drug absorption (e.g., gastrectomy, cholecystectomy,
             or other gastrointestinal tract surgery, except appendectomy).

          3. Immunized (intranasal or injected vaccine) against influenza in the 6 months before
             study entry.

          4. At Screening, an ECG that is abnormal and deemed by the investigator(s) to be
             clinically significant.

          5. For female subjects: Pregnant or nursing subjects and female subjects of childbearing
             potential who are unwilling or unable to use an acceptable method of contraception as
             outlined in this protocol.

          6. For male subjects, unwilling to comply with contraception requirements as outlined in
             the study protocol.

          7. Blood donation (of approximately 1 pint [500 mL] or more) within 56 days before the
             first study drug dose.

          8. Use of the following medications:

               -  Influenza antiviral medication (oseltamivir, zanamivir, rimantidine, or
                  amantadine) within 14 days or ribavirin within 6 months of screening.

               -  Substrates of OATP1B1 and/or OATP1B3, including atrasentan, bosentan, ezetimibe,
                  glyburide, irinotecan, repaglinide, rifampin, telmisartan, valsartan, and
                  olmesartan, from Day 1 through the last dose of study drug. "Statins" (i.e., HMG
                  CoA reductase inhibitors) may be continued, but subjects should be cautioned and
                  observed for potential "statin"-related toxicity. Alternatively, subjects can
                  abstain from statins for the duration of study drug dosing.

               -  Strong inhibitors or inducers of CYP3A metabolism, including carbamazepine,
                  clarithromycin, HIV and HCV protease inhibitors, itraconazole, ketoconazole,
                  nefazodone, phenytoin, posaconazole, rifampin, St. John's wort, telithromycin,
                  and voriconazole from 2 weeks prior to the first dose of study drug until the
                  last PK sample is collected on Day 8.

               -  An investigational drug or device 30 days before the first dose of study drug, 5
                  half lives before the first dose of study drug, or time determined by local
                  requirements, whichever is longest.

          9. History of excessive alcohol consumption.

         10. History of known or current usage of drugs of abuse.

         11. Hospitalized subjects and subjects with bacterial infections requiring systemic
             antibacterial agents at the time of screening.
      