Merck & Co., Inc. is a global health care company that delivers health solutions through its prescription medicines, including biologic therapies, vaccines and animal health products. Its Pharmaceutical segment includes human health pharmaceutical and vaccine products. The Company sells its human health pharmaceutical products primarily to drug wholesalers and retailers, hospitals, government agencies and managed health care providers. It sells these human health vaccines primarily to physicians, wholesalers, distributors and government entities. Its Animal Health segment discovers, develops, manufactures and markets a range of veterinary pharmaceutical and vaccine products, as well as health management solutions and services, for the prevention, treatment and control of disease in all livestock and companion animal species. Its products include KEYTRUDA (pembrolizumab) injection, for intravenous use; WELIREG (belzutifan) tablets, for oral use; Ohtuvayre (ensifentrine) and others.