(NewsNation) — Despite multiple baby formula shipments being flown into the United States from overseas, some parents continue to struggle to find formula on store shelves.

Some doctors say the shortage in the U.S. is not getting worse, but it’s not getting better. Hospitals are running out of samples of formula for parents, and there’s still a concern for babies with specific medical conditions.

According to data from IRI, a market research company, 28.3% of powdered baby formula products were out of stock in U.S. stores this month — up from 23.7% in May.

The Biden administration has taken steps to fix the formula shortage, launching Operation Fly Formula in May to speed up imports from overseas formula producers.

Yet, a big issue that remains is Abbott Nutrition’s production of baby formula. The company’s Michigan factory, which closed in February over contamination, contributed to the national shortage. Production resumed earlier this month. 

Dr. Mark Corkins, nutrition chair of the American Academy of Pediatrics, said he’s not hopeful things will get better immediately.

“We’ve given out a lot of samples, and what we have is pretty much gone at this point. It’s not like we’re on the manufacturers anytime soon because they’re running out, too,” Corkins said.

He continued: “I would love to say, OK, they’re cleaning up the factory, they’re gonna get production rolling. I’d love to say four weeks but I don’t think that’s realistic. I think it’s going to be more at least eight, probably 12. We’ll have to wait and see.”

Many parents continue to turn to alternatives to buying baby formula by turning to Facebook groups and ordering online.

Meanwhile, FDA Commissioner Robert Califf asked on Tuesday for a review of the agency’s food and tobacco programs following months of criticism over their handling of the baby formula shortage and e-cigarette reviews.

“Fundamental questions about the structure, function, funding and leadership need to be addressed” in the agency’s food program, Califf said in a statement. The agency’s tobacco center, which regulates traditional cigarettes and vaping products, is facing challenges navigating policy and enforcement issues from “an increasing number of novel products that could potentially have significant consequences for public health,” he said.