The extent of damage from a tornado that struck a critical Pfizer factory in Rocky Mount, N.C., is now coming into focus.

The first images after the tornado hit it on July 19 showed a roof that was mangled and torn off. The facility makes dozens of medicines used in hospitals across the United States.

Hospitals panicked.

"Every hospital buyer across the country, the second they heard about that tornado, everyone was just, like, 'Buy, buy, buy, buy, buy!'" says Erin Fox, a pharmacy director for the University of Utah Health's hospitals.

They didn't wait to find out which products were affected or how long shortages might last.

Pfizer makes dozens of hospital drugs at the damaged factory

Pharmaceutical companies are reluctant to disclose exactly what they make where. The information is often blacked out on Food and Drug Administration inspection records, for example. The agency's statement following the tornado explained "disclosure laws prevent the FDA from providing a complete list of products made at the facility."

Pfizer declined an interview request.

NPR was able to use records from the National Institutes of Health to compile a list of dozens of drugs that are made there. They cover hundreds of billing codes that comprise different formulations and packages.

The products include a lot of painkillers and anesthetics that are used in hospitals and given intravenously. And there are also drugs like naloxone, which is used to reverse opioid overdoses, and vitamin K, which is used to prevent bleeding in newborns.

According to Pfizer, this site makes about 8% of all sterile injectables used in hospitals across the U.S.

Pfizer makes many of these products only at its Rocky Mount site, NPR found. However, a competing company, like Baxter International, often makes a similar product.

The FDA says fewer than 10 products made by Pfizer at its Rocky Mount factory are sole source. But the agency said there are either substitutes or enough stock in other Pfizer warehouses to minimize disruptions.

Boston University health economist Rena Conti says her research shows only a handful are "backbone" therapies for which there are no real alternatives. "This includes vitamin K1, which is needed for almost every live birth in a hospital," she says, and aminophylline, which can help people who are having trouble breathing.

The FDA is working with Pfizer to assess and mitigate the situation, commissioner Robert Califf said in a statement. The agency said it doesn't anticipate any immediate significant supply disruptions.

Pfizer limited hoarding

The company was able to curtail hoarding fairly quickly, University of Utah's Fox says. Pfizer worked with wholesalers to limit what hospitals could buy to no more than 100% of their usual orders.

Pfizer also sent a letter to health care providers on Friday, explaining that its initial assessment of the damage found that production areas of the Rocky Mount facility were mostly unscathed. The warehouse sustained most of the damage.

The company's letter listed 65 products made at the site that Pfizer thinks might have disruptions based on existing inventory and market share.

A lot of the products were already in shortage, which is good news and bad news, says Fox, who is also a national expert on drug shortages. The bad news is those shortages will continue for things like certain formulations of lidocaine, a local anesthetic. But the good news is hospitals already know how to cope.

"If there had to be this tornado, it seems like this is probably one of the best-case scenarios where, you know, manufacturing lines aren't impacted, and it was an area of the facility that can be fairly quickly rebuilt," Fox says. "And so it's not a time to panic."

She expects the ripple effects of this to last a few months rather than a few years.

Climate change puts drug factories at risk

Conti, of Boston University, says the tornado is a good reminder about the vulnerabilities in the U.S. drug supply. When Hurricane Maria struck Puerto Rico in 2017, the damage caused shortages of IV saline bags.

"Pharmaceutical manufacturing in the United States requires access to water and has traditionally been located in places such as Puerto Rico, the Gulf states and other locations that are now vulnerable to climate change," Conti says.

The weather events could serve as a warning.

Redundancy is also important in the drug supply chain so that when something halts production at one factory — whether it's a tornado or a bad inspection — it's not the end of the world.

"There are approximately 230 drugs in short supply currently in the United States," Conti says. "The Pfizer plant will definitely take down another couple of dozen drugs, and a handful of those will likely go into shortage, or the shortages will become more persistent because of what happened. However, there are somewhere on the order of 6,000 drugs sold into the U.S. market every single day."

She says it's important to remember that despite all the challenges, the U.S. drug supply is resilient and "remarkably high quality."

"Our system remains the gold standard for the world," she says.