Becoming the first pneumococcal conjugate vaccine specifically designed for adults 18 and older, Merck & Co. Inc.’s 21-valent candidate, Capvaxive (V-116), gained U.S. FDA approval on its June 17 PDUFA date. The Rahway, N.J.-based company expects to take significant market share based on positive phase III findings from the Stride-3 trial. Analysts have estimated the product could reach $2 billion in annual global sales.