The FDA, in an internal review, concluded myriad factors, including insufficient emergency response capabilities, led to a nationwide shortage of infant formula that had parents struggling this past spring to find food for their babies.

The scarcity of formula occurred after the FDA received reports of illness or death in infants, and a facility run by the nation’s largest manufacturer of infant formula ceased production.

The FDA’s assessment, which was overseen by 32-year agency veteran Steven M. Solomon, outlined 15 findings as well as recommendations to consider, based on 43 interviews, with 61 employees.

In some respects, the FDA’s response to protect the public from a poorly understood disease—Cronobacter—highlighted unique challenges, considering the role of infant formula as a sole source of nutrition for many babies.

“This incident required an unusual level of agency leadership involvement to assess and weigh risks associated with potential product contamination against risks of essential products being unavailable due to a shortage,” the FDA found in its report published this week. “Typically, product safety is the primary driver during food safety incidents, and product availability does not impact compliance actions.”

Among the report’s recommendations: the FDA will consider alternative actions to abate concerns over the availability of a product like infant formula that serves as the only source of nutrition.

The interviews revealed five major areas of need, including adequate equipment, training, staffing and regulatory authorities to meet the FDA’s mission, Solomon said in a preface to the report.

The FDA also cited the need for “modern information technology” to enable everyone involved in a response to access and exchange data, and modern emergency response systems that can manage several public health emergencies happening at the same time.

The FDA further identified the need for evaluation of the infant formula industry, food safety culture and preparedness, and preventative controls. The agency also said it requires better scientific understanding about Cronobacter and how that could lead to proper control measures and oversight of the disease.

Although rare, Cronobacter infections in infants can be fatal, according to the Centers for Disease Control and Prevention (CDC), which added infections in infants under the age of 1 are frequently associated with powered infant formula.

“Cronobacter is not a nationally reportable disease,” the FDA’s report said, “and scientific gaps in understanding Cronobacter contamination and illness hindered the FDA’s response throughout the incident.”

Solomon, who directs the Center for Veterinary Medicine and spent 23 years in the Office of Regulatory Affairs, which oversees inspectional programs, said the interviews with FDA employees revealed “there is no single action to explain the events that occurred.”

Instead, “the report identifies a confluence of systemic vulnerabilities that demonstrate the need to focus on continued modernization and investment in the expertise and tools needed to better anticipate and address future public health challenges in this area,” he said in a separate statement announcing conclusion of the FDA’s internal review.

The FDA faced ample scrutiny from lawmakers and others in connection to the infant formula crisis. A whistleblower delivered a 34-page report to the FDA in October alleging unsanitary conditions at an infant formula facility operated by Abbott, yet a top official didn’t learn about the complaint until four months later, The Washington Post reported in May.

In its internal report, the FDA acknowledged a complaint that a confidential informant sent to FDA leaders through email and other delivery systems was not sent to the addresses.

“The FDA should identify clear definitions for the terms ‘whistleblower,’ ‘confidential informant’ and ‘informant,’ and develop policies and provide training to staff regarding how to identify, escalate and appropriately manage confidentiality of such complaints,” the FDA recommended in its report.

Abbott Nutrition came under FDA scrutiny after the agency learned four infants who had become sick or died consumed infant formula produced by the company in Sturgis, Michigan. The FDA subsequently launched an investigation and identified insanitary conditions at Abbott’s facility and warned consumers not to use certain products manufactured there.

Abbott Nutrition in February issued a voluntary recall of certain infant formula products at its facility and temporarily stopped production.

“While necessary to safeguard public health, the recall and pause in production further stressed a supply chain already strained by the Covid-19 pandemic,” the FDA stated in its report. “A shortage of these products created hardships for parents and caregivers who rely on infant and specialty formulas to feed their babies, as well as loved ones with certain metabolic disorders.”

Abbott meets and surpasses regulatory requirements for testing of infant formula and “will continue raising the bar by working with FDA and industry partners to further advance infant formula safety and processes,” company spokesman John Koval said in an emailed statement. “Likewise, we have always had a zero-tolerance policy for Cronobacter sakazakii in our plants. That is why we test for it regularly and take steps to eliminate it if/when we find it, and it is why we took the steps we did in Sturgis.”

Since Abbott’s voluntary recall in February, Koval said, investigations conducted by Abbott, the FDA and CDC “did not find any definitive link between the company’s products and illnesses in children.” He added the homes of the four infants tied to the investigation all had unopened containers of formula that tested negative for Cronobacter sakazakii.

In May, more than 40 percent of baby formula supplies in the U.S. were out of stock, according to CNBC in an article published last month. The infant formula shortage has eased, according to national media reports, but lawmakers still have raised concerns over scarcity of supply.

This week, 13 U.S. senators wrote to the head of the FDA regarding the agency’s strategy to restock the supply of infant formula across the country. The letter was delivered to FDA Commissioner Dr. Robert Califf after the FDA responded to a related inquiry from lawmakers.

“Despite the numerous flexibilities and resources provided by Congress and temporary import flexibilities outlined in your letter, the infant formula crisis persists nationwide,” Sens. Bill Cassidy, M.D. (R-Louisiana) and Roger Marshall, M.D. (R-Kansas) wrote to Califf along with 11 of their Republican colleagues in the Senate. “Some of the FDA’s flexibilities are set to expire at the end of this month, and Operation Fly-Formula, while alleviating some issues, cannot run indefinitely. American families need permanent long-term solutions, and that includes increasing capacity and competition in the U.S. market.”

The senators noted three manufacturers control 80 percent of the market, led by Abbott (49.5 percent), Mead Johnson (20.6 percent) and Perrigo (11.9 percent).