Pfizer, the world’s biggest drugmaker, is recalling one batch of its Prevnar pneumonia vaccine because it was filled with expired material, U.S. drug regulators said. Pfizer began the recall on February 10, the Food and Drug Administration said on its website on Tuesday. The recall affected just one wholesaler, meaning the medicine had not yet reached doctors. Prevnar 13 fights pneumonia, meningitis and other diseases caused by pneumococcus bacteria, and was recently approved for use in adults 50 and older. It had previously been approved for children.