WASHINGTON (REUTERS) - Masks will be required indoors in Washington, DC, for everyone aged two years and older starting on Saturday, Mayor Muriel Bowser said on Thursday (July 29), regardless of whether they have been vaccinated against the Covid-19 virus.

The mandate will put the nation's capital in line with updated guidance that the US Centres for Disease Control and Prevention released this week in an effort to contain the rapid spread of the Delta variant of the coronavirus.

Many federal government institutions in Washington and its suburbs have already implemented similar mask requirements and President Joe Biden is expected to announce additional measures for the federal workforce later on Thursday.

In addition, the Smithsonian said it would reimpose mask requirements at its museums that line the National Mall and other indoor venues for visitors two years and older beginning on Friday "regardless of vaccination status."

Face coverings may be removed while eating or drinking in designated areas, it said in a statement on Thursday.

By the beginning of July, Washington had hit its lowest rate of community spread of Covid-19 since the global pandemic began a year and a half ago.

Over the course of the month, the daily case rate has increased fivefold, at the same time that the test positivity rate rose, LaQuandra Nesbitt, director of the city's health department, said at a public briefing before Bowser announced the new mandate.

Current estimates indicate more than half the city's residents have been fully vaccinated, according to public health agency data.