For months, public health officials and members of Congress have wanted to know why the federal government fell short in its efforts to rapidly develop a test to help detect and stop the spread of the novel coronavirus.

Two federal probes are underway into actions at the Centers for Disease Control and Prevention that caused problems with test kits and delayed widespread detection efforts in the United States. But exactly when those examinations will yield answers is unclear, according to Trump administration officials.

The reviews are being led by the headquarters of the Department of Health and Human Services and, separately, by the department’s Office of Inspector General.

Katherine Harris, a spokeswoman for the HHS inspector general’s office, said its audit, opened in mid-April, is exploring what the office has described as “CDC’s process of producing and distributing” the test kits. The findings, she said, are not expected to be made public until 2021.

“We want to do nothing to interfere with ongoing emergency response operations,” Harris said by email.

Bill Hall, a deputy assistant HHS secretary for public affairs, declined to estimate when the separate investigation led by HHS headquarters would probably conclude.

Hall said that investigation, started in early March, seeks to “better understand the nature and source of the manufacturing defect in the first batch of COVID-19 test kits that were distributed to state health departments and others.” Covid-19 is the disease caused by the novel coronavirus.

The CDC’s rollout of the test kits was delayed for weeks after the first batch generated dozens of false-positive results when state and local public health laboratories began trying the kits in late January. The false positives occurred within a component of the test that the CDC later said was not necessary to detect the virus.

The Washington Post reported on April 18 that the false positives were caused by contamination that occurred while the kits were manufactured at the CDC’s facilities in Atlanta. An examination by the Food and Drug Administration concluded that the tests failed because of substandard manufacturing practices and that the CDC had violated its own protocol in making the kits, The Post also reported.

In late February, the FDA recommended that the CDC stop manufacturing the kits and shift production to an outside contractor.

Senior CDC officials had earlier declined to remove the troubled component from the design of the test kits. On Feb. 28, the director of the CDC’s National Center for Immunization and Respiratory Diseases, Nancy Messonnier, publicly characterized the test difficulties observed at the public health labs as “inconclusive results.”

The CDC ultimately followed the FDA’s recommendations, but the delay hindered efforts to detect the virus and to blunt its spread throughout the United States. The CDC has not explained the rationale for the original design or what factors led to the breakdown in manufacturing practices.

In testimony on March 11 before the House Oversight and Reform Committee, CDC Director Robert R. Redfield, an appointee of President Trump, cited the ongoing HHS investigation and declined to discuss details of the test kits’ failure.

Benjamin N. Haynes, a CDC spokesman, said last week that the agency “has implemented enhanced quality control to address the issue” that surfaced with the original test kits.

The CDC’s performance has drawn condemnation from clinicians, public health officials and some members of Congress who linked the delays caused by the troubled test kits to deaths that could have been averted.

“It’s clear CDC’s early testing missteps cost us valuable time, and ultimately invaluable lives, as this virus spread undetected,’’ Sen. Patty Murray (D-Wash.), said by email on Thursday. “People deserve to know what went wrong, and they need to know what we are doing to make sure this never happens again.”

Murray, whose state had the nation’s first confirmed outbreak of the virus, was the first member of Congress to urge the HHS inspector general to investigate. The inspector general’s office made public its opening of the audit on April 15.

Rep. Raja Krishnamoorthi (D-Ill.), who sought at a March 15 congressional hearing to elicit details from Redfield about whether any CDC scientists or administrators had been held accountable for the testing failure, said that crucial questions remain unanswered.

“We’ve got to get at the root of what happened in order to make sure that going forward we actually have our testing situation in order,” Krishnamoorthi said in an interview.

He said that he wants answers about the CDC’s decision-making during the periods between when the first false positives emerged, and when it shifted manufacturing of the kits to the outside contractor.

“I shudder to think how many people we could’ve tested and saved in that interim,” Krishhnamoorthi said.