June 17 (Reuters) - The U.S. Food and Drug Administration approved Merck's next-generation vaccine to protect adults against pneumococcal disease, according to a letter on the health regulator's website on Monday.

(Reporting by Bhanvi Satija, Sneha S K and Puyaan Singh in Bengaluru; Editing by Shailesh Kuber and Shilpi Majumdar)