Xavier Becerra, Secretary of Health and Human Services (HHS), testifies during a Senate Appropriations Subcommittee hearing on June 9, 2021 at the U.S. Capitol in Washington, D.C.
Washington CNN  — 

Covid-19 vaccinations will be required for the more than 25,000 health care staff and volunteers working at the Department of Health and Human Services, Secretary Xavier Becerra announced Thursday.

“Staff at the Indian Health Service (IHS) and National Institutes of Health (NIH) who serve in federally-operated health care and clinical research facilities and interact with, or have the potential to come into contact with, patients will be required to receive the Covid-19 vaccine,” Becerra said in a statement.

The secretary said the vaccination requirement will apply to “employees, contractors, trainees, and volunteers whose duties put them in contact or potential contact with patients at an HHS medical or clinical research facility.”

An HHS official said the requirement is expected to go into effect by the end of September. While all federal workers are required to attest they have been vaccinated or be tested regularly, the HHS and VHA are mandating vaccination without an option to test out.

In addition, US Surgeon General Vivek Murthy announced Thursday that members of the Public Health Service Commissioned Corps must also be vaccinated. Those public health officials are included in the 25,000 figure, an HHS official said.

The vaccine requirements are the latest move by the White House to require or encourage vaccine mandates in an urgent effort to boost vaccinations in the face of the Delta variant. The announcements add to a growing list of vaccine requirements instituted by various federal departments and agencies for their employees in recent days. On Monday, Defense Secretary Lloyd Austin said he was moving to have all active-duty members of the US military vaccinated against the virus, and last month, President Joe Biden announced that all federal employees must attest to being vaccinated against Covid-19 or face strict protocols.

The statement from HHS noted that “IHS, NIH and the Commissioned Corps already require such personnel to receive the seasonal influenza vaccine and other routine vaccinations, with processes for medical and religious exemptions.”

“As President Biden has said, we are looking at every way we can to increase vaccinations to keep more people safe, and requiring our HHS health care workforce to get vaccinated will protect our federal workers, as well as the patients and people they serve,” Becerra said.

The Department of Veterans Affairs will also expand its vaccine mandate for health care workers at Veterans Health Administration facilities on Friday, requiring most employees, volunteers and contractors at those facilities to be vaccinated, according to a release from the department. The mandate previously applied to physicians working at those facilities.

With the expanded mandate, that list grows to include workers such as psychologists, pharmacists, social workers, nursing assistants, physical therapists, respiratory therapists, peer specialists, medical support assistants, engineers, housekeepers and other clinical, administrative and infrastructure support employees who come into contact with VA patients and health care workers, according to the department.

After first focusing on boosting vaccine supply then ramping up vaccinations through incentives, officials say the administration is now focused on requirements and “the unique ability” of employers to get more adults vaccinated.

A White House official said Biden’s requirement that all federal workers attest that they have been vaccinated or face regular coronavirus testing was established after conversations with business leaders, aiming to establish a model for the private sector to follow. Several major companies have since followed suit and instituted similar requirements in recent weeks.

The White House now hopes that the latest requirements at HHS and the VA will help “keep this snowball moving” in the direction of more vaccine requirements in the private sector, the official said.

The White House’s coronavirus response team is still considering a range of other measures to boost vaccinations and push back against efforts by Republican governors to ban mask mandates.

“We will continue to look at every lever that the federal government can pull,” a White House official said.

CNN’s Barbara Starr, Kaitlan Collins and Zachary Cohen contributed to this report.