WASHINGTON — The Trump administration on Thursday released new requirements for states to report coronavirus data based on race, ethnicity, age and sex of individuals tested for the virus, responding to demands from lawmakers for a clearer picture of the pandemic and its racial discrepancies.

All laboratories — as well as nonlaboratory facilities offering on-site testing and in-home testing — will be required to send demographic data to state or local public health departments based on the individual’s residence, according to details released by the Department of Health and Human Services.

The new guidelines came as Dr. Robert R. Redfield, the director of the Centers for Disease Control and Prevention, faced a barrage of questions from House lawmakers at a health subcommittee hearing about his agency’s often-halting response to the pandemic, and what some members of Congress said was its failure to anticipate and explain the pandemic’s effect on black and Hispanic communities.

“We didn’t have the data we needed to be able to answer that in a responsive way,” Dr. Redfield conceded.

The health department announced the new requirements as large protests continued across the nation over the death of George Floyd after a white police officer knelt on his neck for nearly nine minutes. The virus continues to infect and kill black people in the United States at disproportionately high rates, according to data from some cities and states. And epidemiologists fear the mass protests could set off a new wave of infection.

Fine-grained data on the race and ethnicity of Covid-19 patients may help the government begin to address health inequities by marshaling resources to particularly hard-hit regions of the country. In its announcement, the department said the data would assist with epidemiologic investigations and contact tracing, and help states anticipate supply chain problems.

The data will be stripped of identifying information for privacy reasons but will be publicly available, said Adm. Brett P. Giroir, an assistant health secretary and the federal government’s lead on coronavirus testing efforts.

The deadline for states to start sending such data to the health department is Aug. 1, but Admiral Giroir said he expected many states to begin earlier. “We definitely recognize the importance of doing this quickly,” he said.

As part of the Paycheck Protection Program and Health Care Enhancement Act, signed into law in April, the Trump administration was required to include demography in its Covid-19 analyses. But the results have been slim. In May, the Department of Health and Human Services sent a brief report signed by Dr. Redfield that mostly included links to coronavirus data on the C.D.C.’s website.

Senator Elizabeth Warren, Democrat of Massachusetts, wrote on Twitter at the time that the department should “be embarrassed by the lazy, incomplete, 2.5-page copy-and-paste job it calls a ‘report’ on the racial disparities of Covid-19 cases.”

Racial disparities in the pandemic were the subject of a separate virtual briefing held on Thursday by the House’s select subcommittee on the coronavirus. The data the administration has provided is “grossly inadequate,” said Representative James E. Clyburn of South Carolina, the No. 3 House Democrat and chairman of the committee.

Testing and death rates during the pandemic have put a spotlight on longstanding racial disparities in access to quality health care. In Washington’s predominantly black neighborhoods, for example, the number of deaths is the highest in the city even though the rate of infection is the highest in one of the city’s more mixed-race and income wards.

Dr. Uché Blackstock, an African-American physician and founder of Advancing Health Equity, a health care advocacy group, told the committee that many of her black patients do not have access to testing and, because their disease goes undetected, they do not get the treatment they need.

“I have never been as scared for my patients as I have been the last few months,” she said.

In his opening statement and in several answers to questions from committee members, Dr. Redfield acknowledged the ravages of the virus on what he called “vulnerable” parts of the population.

“I personally want to apologize for the inadequacy of our response,” he told Representative Barbara Lee, a California Democrat who asked about the scanty May report.

In one especially sharp exchange at Thursday’s hearing, Representative Katherine M. Clark, Democrat of Massachusetts, noted that the C.D.C.’s website already contained pages of material on what she called “disparate health outcomes” for people of color.

“Wasn’t it eminently predictable that Covid-19 would disproportionately impact black, Latinx, and Indigenous communities?” she said.

Dr. Redfield responded that it became clear, but only after the agency “stepped back and understood certain social factors in living conditions would be critical.”

He framed the scarcity of demographic information as a consequence of antiquated technology in public health systems, something health experts say contributed to the C.D.C.’s slow grasp of the virus’s spread. “We have a long way to go,” he said.

He also said state governments should sharply increase the number of contact tracers, who can identify anyone who comes into contact with an infected person, to 100,000 by September — well beyond the 600 C.D.C. employees and thousands of state-hired workers currently deployed. He said the C.D.C. would help each state understand the number of tracers it needed.

“It is fundamental that we have a fully operational contact-tracing work force,” he said, “so that we can stay in containment mode as we get into the fall and winter.”

Dr. Redfield also faced testy questions about the inconsistent use of face masks in many states, and he urged Americans to continue physical distancing. At one point, Representative Rosa DeLauro, Democrat of Connecticut and the chairwoman of the subcommittee, displayed a photo of a large crowd at the Lake of the Ozarks over Memorial Day weekend, prompting Dr. Redfield to shake his head.

But mask use is sporadic at the police brutality protests as well, and Democrats have been less critical of the demonstrators. Dr. Redfield said that protests in several cities had the potential to become “seeding events” for the virus, and that attendees should consider getting tested within a week.

Dr. Redfield admitted that the C.D.C. was struggling in its campaign to persuade Americans to wear cloth masks in public, which began in early April, well after the virus had spread to every pocket of the country.

“We’re very concerned that our public health message isn’t resonating,” he said.

President Trump has regularly declined to wear a mask in public appearances, saying that he did not “see it for myself.” Some Republicans have followed the president’s lead, characterizing face masks as tools in a culture war. Representative Andy Harris of Maryland, a physician, claimed at the Thursday hearing that there was now a “cult of masks.”

“I’m afraid to get a picture taken and be without a mask somewhere because someone will say, well, ‘How can you possibly — you’re a doctor — how can you not wear a mask?’” he said.

Dr. Redfield returned to the idea of mask-wearing when asked about the risks of the virus spreading at large protests, where the police’s use of tear gas may cause people to cough virus-laden droplets.

“These social-distancing strategies that we learned are something we need to perfect,” he said. “We’re going to need them to be our major defense again in October, November and December.”

Sheryl Gay Stolberg contributed reporting.