Dr. Anthony Fauci, director of the National Institute for Allergies and Infectious Diseases (left), speaks to Dr. David Kessler, Chief Science Officer of the White House COVID-19 Response Team on the Federal Coronavirus Response on Capitol Hill March 18, 2021 in Washington, DC.

Susan Walsh | Getty Images

The House’s coronavirus subcommittee will hear from three leading health officials in the Biden government on Thursday about United States efforts to step up vaccinations as Covid cases, including those of dangerous variants, are on the rise.

The hearing, which will also focus on the continued need for people to wear masks and follow social distancing measures, is slated to begin at 10:30 a.m. ET. It is streamed live.

The event comes two days after dozens of states abruptly stopped administering Johnson & Johnson’s single-dose Covid vaccine in response to the Food and Drug Administration’s recommendation to suspend those recordings while investigating cases of women, who developed a rare bleeding disorder.

Some fear the recommendation, issued in response to six reported blood clot cases from nearly 7 million J&J doses administered, could hamper the global campaign to vaccinate the world against the pandemic.

The selected subcommittee on the coronavirus crisis, led by James Clyburn, DS.C., is led by Dr. Anthony Fauci, the country’s foremost infectious disease expert, and the director of the Center for Disease Control and Prevention Dr. Rochelle Walensky. David Kessler, a senior Covid official in President Joe Biden’s Department of Health and Human Services, is also on the witness list.

Dr. Rochelle Walensky, director of Centers for Disease Control and Prevention, listens to the response from Covid-19, DC during a hearing with the Senate Committee on Health, Education, Labor and Pensions on March 18, 2021 in Washington on Capitol Hill, DC .

Anna Moneymaker | Getty Images

While the US is vaccinating more people than ever before, Covid cases are increasing in more than half of its states. According to the Johns Hopkins University, an average of more than 71,000 cases per day were counted for the past week.

“It’s almost a race between vaccinating people and this surge that is apparently about to increase,” Fauci told CNN on Wednesday.

The emergence of variants of Covid – like B 1.1.7, which recently flooded Michigan and is now the most common strain in the US – has led health officials to urge Americans to continue to take precautionary measures despite accelerated vaccination efforts.

Experts say Johnson & Johnson’s recent vaccination problems could fuel skepticism about vaccines.

In their quest to have all eligible individuals in the U.S. vaccinated against Covid, officials have stressed that all of the options available – from Pfizer-BioNTech, Moderna and Johnson & Johnson – are safe and effective. All three have been approved by the FDA for emergency use. Pfizer and Moderna vaccines require two separate doses given three to four weeks apart.

But the six cases of women who developed the rare blood clots urged the FDA to stop J & J’s shot “out of caution.”

All women developed the disease within about two weeks of being vaccinated, health officials told reporters Tuesday. One of the women died.

“I think it will affect the hesitation, period. Whether it should or not is a different matter,” said Dr. Jeffrey Kahn, director of the Berman Institute of Bioethics at Johns Hopkins University, told CNBC.

With Johnson & Johnson’s vaccine only containing one dose, experts say the hiatus could also reduce vaccine access for some communities.

“This vaccine was biased to be used in harsher environments, places where you couldn’t deliver two doses. You wanted to deliver one dose and stick to the vaccination schedule,” said Dr. Scott Gottlieb, who sits on the Pfizer board of directors at CNBC on Tuesday.

– The Associated Press contributed to this report.

Disclosure: Scott Gottlieb is a CNBC employee and a member of the boards of directors of Pfizer, genetic testing startup Tempus, health technology company Aetion Inc., and biotech company Illumina. He is also co-chair of Norwegian Cruise Line Holdings and Royal Caribbean’s Healthy Sail Panel.