Inclusion Criteria:

          -  Has histologically or cytologically-confirmed diagnosis of R/M HNSCC that is
             considered incurable by local therapies

          -  Male participants refrain from donating sperm plus are abstinent from heterosexual
             intercourse or agree to use contraception during the intervention period and for at
             least 95 days after carboplatin/paclitaxel

          -  Female participants are not pregnant or breastfeeding and are either not a woman of
             child-bearing potential (WOCBP) or use a contraceptive method that is highly effective
             or are abstinent from heterosexual intercourse during the intervention period and for
             at least 120 days after pembrolizumab or 30 days after paclitaxel or 6 months after
             carboplatin whichever occurs last, and agree not to donate or freeze eggs during this
             period

          -  Has adequate organ function

        Exclusion Criteria:

          -  Has disease that is suitable for local therapy administered with curative intent

          -  Has a life expectancy of less than 3 months and/or has rapidly progressive disease

          -  Has a diagnosed and/or treated additional malignancy within 5 years prior to
             allocation with the exception of curatively treated basal cell carcinoma of the skin,
             squamous cell carcinoma of the skin, curatively resected in situ cervical cancer and
             curatively resected in situ breast cancer

          -  Has received a live vaccine within 30 days prior to the first dose of study
             intervention

          -  Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
             or any other form of immunosuppressive therapy within 7 days prior to the first dose
             of study intervention

          -  Has known active central nervous system (CNS) metastases and/or carcinomatous
             meningitis

          -  Has a history of or current non-infectious pneumonitis that requires steroids

          -  Has an active infection requiring systemic therapy

          -  Has a known history of human immunodeficiency virus (HIV) infection

          -  Has a known history of Hepatitis B or Hepatitis C virus infection

          -  Has had an allogenic tissue/solid organ transplant