(NewsNation) — More than 9,000 tins of baby formula arrived at LAX Monday morning and are expected to hit store shelves as early as next week.

New information revealed Monday shows that according to federal records, the three biggest baby formula manufacturers were never inspected in 2020 due to the pandemic.

U.S. regulators have historically inspected baby formula plants at least once a year.

When they finally did get inside an Abbott Nutrition formula plant in Michigan after a two-year gap, they found standing water and lax sanitation procedures. But inspectors offered only voluntary suggestions for fixing the problems, and issued no formal warning.

Inspectors would return five months later after four infants who consumed powdered formula from the plant suffered bacterial infections. They found bacterial contamination inside the factory, leading to a four-month shutdown and turning a festering supply shortage into a full-blown crisis that sent parents scrambling to find formula.

The gap in baby formula plant inspections, brought on by the COVID-19 pandemic, is getting new scrutiny from Congress and government watchdogs investigating the series of missteps that led to the nationwide infant formula shortage.

The Biden Administration issued a crisis plan that included sending millions of tons of baby formula from overseas called “Operation Fly Formula.” The first successful shipment of infant formula landed in Indianapolis, Indiana, on May 22.

A recent bill would require the Food and Drug Administration to inspect infant formula facilities every six months. And the government’s inspector general for health has launched an inquiry into the FDA’s handling of Abbott’s facility, the largest in the U.S.

Abbott resumed production at the plant early this month under a legally binding agreement with the FDA, but the shutdown and nationwide shortage exposed how concentrated the industry has become in the U.S., with a handful of companies accounting for roughly 90% of the market.

As COVID-19 swept across the U.S. in early 2020, the FDA pulled most of its safety inspectors from the field, skipping thousands of routine plant inspections.

The FDA did conduct more than 800 “mission critical” inspections during the first year of the pandemic, the agency said in a statement. Regulators selected facilities for inspections based on whether they carried a specific safety risk or were needed to produce an important medical therapy.

Only three of the nation’s 23 facilities that make, package or distribute formula made the cut. The FDA resumed routine inspections in July 2021.

The inspection records reviewed by the AP show gaps as large as 2 1/2 years between FDA’s 2019 inspections and when regulators returned to plants owned by the three leading formula manufacturers: Abbott, Reckitt and Gerber.

In fact, the FDA still has yet to return to one key plant owned by Reckitt and two owned by Gerber, according to agency records. All those facilities are operating around the clock to boost U.S. formula production.

The Associated Press contributed to this report.