The drugmaker reopened the site on Aug. 7 and said efforts to restart production are on track, with several areas of the site now operational, including its Incoming Materials, Chemical and Biological Quality labs, packaging and inspection operations and supply chain and warehouse.

Pzifer has been scrambling to get production back on track at Rocky Mount after a tornado ripped through the facility last month, causing extensive damage to its warehouse. All 40,000 pallets of packaging supplies and finished goods in the company's warehouse were damaged.

The shutdown of the site — which produces nearly 50 types of drugs, including about a quarter of Pfizer's sterile injectable drugs such as painkillers and anesthesia — sparked worry about shortages across the country. The site produces 8% of U.S. supply of sterile injectable drugs.