WASHINGTON (AP) – The Director of the Centers for Disease Control and Prevention says schools can safely reopen even if teachers are not vaccinated for the coronavirus.

CDC Director Rochelle Walensky made the remarks Wednesday during a White House COVID-19 press briefing.

As some teachers’ unions balk at resuming in-person instruction before teachers are inoculated, Dr. Rochelle Walensky says, “Vaccination of teachers is not a prerequisite for safe reopening of schools.”

Walensky cited CDC data showing that social distancing and wearing a mask significantly reduce the spread of the virus in school settings.

White House COVID-19 coordinator Jeff Zients called on Congress to pass additional funding to ensure schools have the resources necessary to support reopening.

President Joe Biden has pledged to ensure nearly all K-8 schools will reopen for in-person instruction in the first 100 days of his administration.

Teachers are prioritized as “essential workers” under the CDC’s vaccination plans, though many have yet to receive doses as the nation continues to face a supply shortage of the vaccine.

For most people, the new coronavirus causes mild or moderate symptoms. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia and death.

The United States has nearly 26 million confirmed cases of COVID-19, according to data from Johns Hopkins University.

As of Wednesday, the U.S. had more than 446,000 deaths from the virus. Worldwide, there are more than 103 million confirmed cases with more than 2.2 million deaths.