WASHINGTON (AP) - Abbott Nutrition has restarted production at the Michigan baby formula factory that has been closed for months due to contamination, the company said Saturday, taking a step toward easing a nationwide supply shortage expected to persist into the summer.

The February shutdown of the largest formula factory in the country led to the supply problems that have forced some parents to seek formula from food banks, friends and doctor’s offices.

Abbott said it initially will prioritize production of its EleCare specialty formulas for infants with severe food allergies and digestive problems who have few other options for nutrition. The company said it will take about three weeks before new formula from the plant begins getting to consumers.

“We will ramp production as quickly as we can while meeting all requirements,” Abbott said.

The plant’s reopening is one of several federal actions that are expected to improve supplies in the weeks ahead. President Joe Biden’s administration has eased import rules for foreign manufacturers, airlifted formula from Europe and invoked federal emergency rules to prioritize U.S. production.

Abbott closed the Sturgis, Michigan, factory in February after the Food and Drug Administration began investigating four bacterial infections among infants who consumed powdered formula from the plant. Two of the babies died. FDA inspectors eventually uncovered a host of violations at the plant, including bacterial contamination, a leaky roof and lax safety protocols.

Abbott’s February recall of several leading brands, including Similac, squeezed supplies that had already been strained by supply chain disruptions and stockpiling during COVID-19 shutdowns.

The shortage has been most dire for children with allergies, digestive problems and metabolic disorders who rely on specialty formulas. The Abbott factory is the only source of many of those products, providing nutrition to about 5,000 U.S. babies, according to federal officials.