(NEXSTAR) – To combat an infant formula shortage, federal regulators have given the company behind a nationwide recall permission to release some of its previously produced powdered formula to individuals on a case-by-case basis.

In February, the U.S. Food and Drug Administration launched an investigation into Abbott Nutrition’s Sturgis, Michigan, facility after receiving complaints of Cronobacter sakazakii and Salmonella Newport infections among infants.

In total, four cases of infant illness after being exposed to certain brands of formula from Abbott’s facility have been included in the investigation. Two infants have died, and Cronobacter infection may have been a contributing cause for both, according to the FDA.

The recall includes products from three different brands – Similac, Alimentum, and EleCare – and has left parents and caregivers scrambling to find formula. New retail data has found the shortage of infant formula may have worsened even more in recent weeks.

Some retailers, like Walgreens and CVS, have had to impose purchasing limits on baby formula.

While the FDA continues to work with Abbott and other formula manufacturers to increase new production, the agency has given Abbott permission to release products “to individuals needing urgent, life-sustaining supplies.”

These formulas were produced at Abbott’s Sturgis facility earlier this year and carry a risk of being contaminated, the FDA warns. Those formulas eligible for release on a case-by-case basis are:

• Glutarex-1
• Glutarex-2
• Cyclinex-1
• Cyclinex-2
• Hominex-1
• Hominex-2
• I-Valex-1
• I-Valex-2
• Ketonex-1
• Ketonex-2
• Phenex-1
• Phenex-2
• Phenex-2 Vanilla
• Pro-Phree
• Propimex-1
• Propimex-2
• ProViMin
• Calcilo XD
• Tyrex-1
• Tyrex-2
• Similac PM 60/40

The FDA said in a new update to the investigation that the agency is still concerned about the health risks infants requiring certain formulas could suffer without it.

“In these circumstances, the benefit of allowing parents, in consultation with their healthcare providers, to access these products may outweigh the potential risk of bacterial infection,” the FDA said. Still, the FDA recommends parents and caregivers speak with their doctor to weigh the risks and see whether comparable alternatives are appropriate.

Parents and caregivers who would like access to the above formulas are encouraged to contact Abbott directly to request the product by calling 1-800-881-0876. Those who receive and use the above formulas should follow the preparation instructions listed on the containers and monitor the infant’s health for any changes.

If any changes are noticed, a doctor should be notified immediately, according to the FDA.

The agency continues to warn against using recalled Similac, Alimentum, or EleCare powdered formulas. Parents and caregivers should not dilute infant formula, or make or feed homemade formula to infants. Do not purchase imported formula online, as it could be counterfeit, the FDA added.