Medicaid enrollment soared during the coronavirus pandemic, with nearly 10 million Americans joining the public health program for the poor by January, a government report released Monday shows.

80 million people – more than ever in the history of the program – are now on Medicaid insurance, which is shared by the state and the federal government. The new figures show the increasingly important role of the program not only as a safety net, but also as a pillar of American health insurance, which covers a quarter of the population.

“The purpose of Medicaid during times like these is when there is an economic downturn,” said Peggah Khorrami, a researcher at Harvard Chan TH School of Public Health who has studied the program’s surge in enrollments during the pandemic. “As people lose their jobs, Medicaid comes in and we insure people that way.”

The Affordable Care Act transformed Medicaid from a targeted health service aimed at helping specific groups of people – such as expectant mothers and people with disabilities – to a much broader program that provides largely free insurance to most people below a certain income threshold. The exception is in 12 states, mostly in the South, that have resisted expanding Medicaid under the Health Act to cover all adults on incomes up to 138 percent of the poverty line, which would be $ 17,774 for one person this year .

However, the expansion of Medicaid in most states since most of the ACA came into effect in 2014 has proven important during the pandemic, creating a public source of protection for the newly unemployed that did not exist a decade ago. Adult enrollment at Medicaid grew twice as fast as child enrollment in the past year, suggesting that widespread job loss related to the pandemic has created a large group of newly eligible adults.

“There has been significant growth in Medicaid enrollments over the past economic downturn, but their focus has been on children,” said Rachel Garfield, co-director of the Medicaid and Uninsured Program for the Kaiser Family Foundation. “This time around, it’s interesting that a lot of the enrollment is among adults.”

Ms. Garfield also noted that Medicaid coverage rose much faster during this recession than in previous downturns. At the start of the Great Recession in 2009, fewer than 4 million Americans joined the program.

There may also be increased interest among uninsured Americans who were previously eligible for Medicaid but only chose to enroll because of heightened health concerns during the pandemic.

“The surge we are seeing is exactly how Medicaid works: the program steps in to support people and their families during difficult times,” said Chiquita Brooks-LaSure, who oversaw the Medicaid program, in a Biden administration Explanation.

In the years before the pandemic, the number of Medicaid enrollments had decreased. More than a million children lost insurance coverage between December 2017 and June 2019, a trend that rocked health care proponents. Many attributed the changes to new rules during the Trump administration that made it more difficult to sign up for the benefits.