The CDC is expected to revise its guidance regarding masks for those who are vaccinated amid concerns over variants.

On Tuesday, Apoorva Mandavilli reported for the New York Times that the CDC was widely believed to be set to recommend this week that those who are vaccinated against COVID-19 “resume wearing masks indoors under certain circumstances.” According to Mandavilli, the revised guidance could arrive as soon as Tuesday, while a separate CNN report claimed the update could be unveiled later this week.

In May, the CDC had updated its mask guidance to let those who were fully vaccinated know they could safely resume a variety of maskless activities, including in many indoor areas. The expected update this week would mark a partial walking back of that guidance and is inspired by the twofold problem of a less-than-ideal nationwide vaccination rate and concerning numbers associated with the Delta variant.

Prior to the expected revisions that made headlines on Tuesday, the most recent update to the agency’s interim public health recommendations for fully vaccinated people focused on adding in considerations for those who are immunocompromised.