U.S. hospital drug supplies may be strained further after a tornado ripped open the roof of a Pfizer factory this week. The company says its factory near Rocky Mount, North Carolina, makes nearly 25% of Pfizer's sterile injectable medicines used in U.S. hospitals. Pfizer says all employees were accounted for after Wednesday's storm. It also says it is still assessing damage. Experts say the damaged plant could lead to a supply disruption while Pfizer figures out next steps. Those could include shifting production to another location.