After World Health Organization officials urged fully vaccinated people to continue wearing masks out of concern about the global spread of the Delta variant, New York City and Los Angeles County appear to now be taking slightly diverging approaches.
New York and California lifted virtually all coronavirus restrictions on businesses and social gatherings nearly two weeks ago, signs of immense progress after New York City and Los Angeles County suffered devastating waves of the virus. Both states have followed the Centers for Disease Control and Prevention’s mask guidance that allowed for fully vaccinated people to go maskless in most situations. (Exceptions remained for health care settings and public transit, among others.)
On Monday, though, Los Angeles County said that it strongly recommended that everyone wear masks indoors regardless of vaccination status as a precaution against the Delta variant. By contrast, Mayor Bill de Blasio of New York City said on Tuesday that fully vaccinated municipal office employees are no longer required to wear masks or adhere to social-distancing protocol inside their offices. Unvaccinated municipal workers and those who interact with the public must continue to wear masks.
“We will make adjustments when we see real, consistent evidence, but so far, the data is telling us, in fact, things keep moving in the right direction,” Mr. de Blasio said at a news conference.
Public health experts generally agree that getting vaccinated offers the best protection against any type of the virus, and that the Delta variant is unlikely to pose much risk to people who have been fully vaccinated.
As of Monday, Los Angeles County had a daily average of three new virus cases per 100,000 people over the past week, while New York City had a daily average of two per 100,000 over the same time period, according to a New York Times database.
In Los Angeles County, where 50 percent of residents are fully vaccinated, the Delta variant accounted for nearly half of all cases sequenced in the week ending June 12, the Los Angeles County Department of Public Health said on Monday.
“Until we better understand how and to who the Delta variant is spreading, everyone should focus on maximum protection with minimum interruption to routine as all businesses operate without other restrictions,” county officials said in a statement, noting that social distancing and capacity limits are not required.
When the C.D.C. issued its mask guidance on May 13, New York State adopted it within a few days, though New York City’s health commissioner still recommended residents wear masks indoors.
As of Tuesday morning, about 60 percent of the city’s adult residents and about 51 percent of all residents have been fully vaccinated, according to the city’s health data.
About 80,000 workers were required to return to the office on May 3, after more than a year of remote work, in a signal that the city was beginning to reopen.
Still, officials have been cautiously watching the Delta variant, worried about a possible resurgence of cases as restrictions have eased, the city has reopened and New Yorkers scarred from the restrictions and trauma of last year have resumed gathering together.
“Right now, we are winning the race against the Delta variant,” Mr. de Blasio said, adding that he did not expect the city to reimpose restrictions or shut down again.
As of June 12, the last date for which data is available, 22.7 percent of new cases in the city were identified as the Delta variant, the city’s health data shows, though the rate comes from a relatively low sample of about 100 cases.
So far there has been little evidence that fully vaccinated New Yorkers need to take greater precautions because of the Delta variant, said Mitchell Katz, the chief executive of the city’s public hospital system.
“Overwhelmingly, the vaccine works against the Delta variant, and so people can keep their masks off if they’ve been fully vaccinated,” Mr. Katz said.
In Chicago, the top health official on Tuesday said during a social media question-and-answer session that the city would be sticking with the C.D.C.’s guidance.
“Right now, while our outbreak remains in very good control locally, even with the Delta here, there’s not a reason to adjust that guidance,” said Dr. Allison Arwady, the commissioner of the Chicago Department of Public Health.
Daniel E. Slotnik and Neil Vigdor contributed reporting.