Starting Friday, all visitors — even those who are vaccinated — must wear masks at the Smithsonian Institution’s museums and indoor spaces, it said Thursday.

The move is a reversal from the Smithsonian’s announcement last month that visitors who have been vaccinated didn’t need to wear masks indoors.

The change in policy, which applies to those who are 2 years old and above, follows new Centers for Disease Control and Prevention guidelines recommending mask-wearing indoors as coronavirus rates are rising across the United States, including in the District.

The Smithsonian, which has several major museums downtown as well as the popular National Zoo, typically attracts more than 28 million visitors a year. Many of its facilities were closed during the height of the global pandemic and later reopened with ticketed time slots.

The Smithsonian, which began a gradual reopening of its museums in May, stopped requiring fully vaccinated visitors to wear masks indoors June 28.

In its statement Thursday, the Smithsonian said those who are fully vaccinated do not have to wear a mask in outdoor areas at the National Zoo and the Smithsonian’s outdoor gardens. All visitors, regardless of vaccination status, must wear a mask in restrooms, officials said.

“This change follows the most recent guidance from the Centers for Disease Control and Prevention (CDC), which recommends that fully vaccinated individuals wear masks indoors in areas of substantial transmission rates of COVID-19,” the statement read. “The Smithsonian welcomes visitors from all over the globe, and will require masks to protect the health and safety of staff and visitors at its locations in the Washington, D.C. area and in New York City.”