by Michael Erman and David Ljunggren

(Reuters) – This is where the most damage was caused by the tornado pfizer Inc (NYSE: )’s Rocky Mount, North Carolina plant was for warehousing, not manufacturing facilities, CEO Albert Bourla said Friday, downplaying concerns about long-term drug shortages from the plant.

The tornado that hit the site on Wednesday completely destroyed the warehouse, but caused no major damage to production facilities there.

Nonetheless, Bourla told a news conference in Rocky Mount that repairing the damage would be a major task. It will take several weeks to restart facilities at the plant, even if there is no structural damage.

“We are working at full speed to restart this manufacturing plant,” Bourla said. He said crews were working to restore power to the plant. Meanwhile, the company is trying to identify alternative manufacturing locations in the US.

The Rocky Mount plant is one of the largest factories for sterile injectable drugs in the world. Its products include anesthesia, pain relievers and anti-infectives for use in hospitals.

About 25% of Pfizer’s sterile injections used in US hospitals are produced there, according to the company’s website.

The number of US drug shortages is already near a 10-year high, according to the American Society of Health-System Pharmacists, and shortages caused by the damage at the Pfizer plant could put further pressure on hospitals.

Bourla said Pfizer has about six weeks’ worth of inventory, so hospitals won’t feel absences or production for a few weeks.

The US Food and Drug Administration said late Friday that it is working closely with Pfizer to assess the impact of the damage at its facility, adding that it does not expect an immediate significant impact on supplies because the products are currently in hospitals and in the distribution system.

The FDA said it has taken mitigation steps for products that may already be or may be produced at this plant, by seeking additional sources and by asking other manufacturers to be prepared to increase production if needed.

Soumi Saha, senior vice president of government affairs at Premier Inc., a company that buys drugs on behalf of hospitals and health care systems, said the impact of warehouse damage would be less severe than if manufacturing sectors were severely hit.

“Damage to a storage facility will have some downstream impact, but it should be fairly minor and short-lived, whereas sustained damage to a manufacturing or production facility could mean longer-term effects and greater severity of shortages,” Saha said in an interview.

Pfizer has not disclosed the specific products that will be made at the plant. However, Lisa Mulloy, chief pharmacy officer at Northwell Health in New York, said the health care system’s procurement team was working to buy the two pain drugs, hydromorphone and fentanyl, from other manufacturers and wholesalers.

“Health systems are probably just ordering, ordering, ordering as much as possible, which can actually add up and create other shortages,” said Erin Fox, senior director of drug information at University of Utah Health.