New York City will require all workers at city-run health care facilities and hospitals to be vaccinated or take weekly Covid tests, with positivity rates continuing to tick upward as the delta variant spreads, City Hall officials told NBC New York.

Mayor Bill de Blasio will release details regarding the requirement, including who that includes, Wednesday morning, sources said. The plan is aimed at the one-third of all health care and hospital workers in the city still not vaccinated.

“It’s all about the safety of a health care setting,” said Bill Neidhardt, the mayor’s press secretary.

This is a developing story. Please check back for updates.