NEW YORK — Over 460 former employees of the nation’s leading public health agency received notifications on Wednesday that they are being rehired, as reported by a union representing these workers.

The U.S. Department of Health and Human Services confirmed that letters of reinstatement had been sent to the ex-employees of the Centers for Disease Control and Prevention, though they disclosed few additional details.

About 2,400 CDC employees lost their jobs in a wave of cuts across federal health agencies in early April, according to a tally at the time.

Entire programs at the CDC were effectively dismantled, including those targeting smoking, lead poisoning, gun violence, asthma, air quality, and workplace safety and health. The office responsible for handling Freedom of Information Act requests was completely closed. Programs dealing with infectious diseases also suffered, affecting efforts to combat outbreaks abroad, labs working on HIV and hepatitis in the U.S., and personnel focused on eradicating tuberculosis.

An estimated 200 of the reinstated workers are based in the CDC’s National Center for HIV, Viral Hepatitis, STD, and Tuberculosis Prevention, HHS officials confirmed. Staffers at a CDC lab that does testing for sexually transmitted diseases are being brought back, said one CDC employee who wasn’t authorized to discuss what happened and spoke to The Associated Press on condition of anonymity.

Also reinstated are an estimated 150 employees at the CDC’s National Center for Environmental Health, including people staffing a lab that works on lead poisoning, according to the union and employees.

Layoffs at federal agencies were challenged in lawsuits, with judges in some cases ordering federal agencies to halt terminations of employees.

Officials at HHS have never detailed how they made the layoff decisions in the first place. And they did not answer questions about why the notices went out, or how decisions were made about who to bring back.

HHS spokesperson Andrew Nixon said the agency was streamlining operations and that “the nation’s critical public health functions remain intact and effective.”

“The Trump ministration is committed to protecting essential services — whether it’s supporting coal miners and firefighters through NIOSH, safeguarding public health through lead prevention, or researching and tracking the most prevalent communicable diseases,” he said.

The reinstatements don’t undo the damage being done by Kennedy and the Trump administration to federal public health, said members of Fired But Fighting, a group of affected CDC workers who have helped organize rallies in Atlanta. The most recent was in the rain on Tuesday, at which some attendees called for Kennedy to resign.

“Bringing a few hundred people back to work out of thousands fired is a start, but there are still countless programs at CDC that have been cut, which will lead to increased disease and death,” one of the group’s founding members, Abby Tighe, said in a statement.

This is not the first time that employees at the Atlanta-based agency were told they were being terminated only to then be told to come back. After an earlier round of termination notices went out in February, about 180 CDC employees in March were told to come back.