Throughout the pandemic, masks have ranked among the most contentious public health measures in the United States, symbolizing a bitter partisan divide over the role of government and individual liberties.

Now, with a new variant of the coronavirus rapidly spreading across the globe, masks are again the focus of conflicting views, and fears, about the course of pandemic and the restrictions required to manage it.

The renewed concerns follow the wildfire growth of the Delta variant, a highly infectious form of the virus first detected in India and later identified in at least 85 countries. It now accounts for one in five infections in the United States.

In May, federal health officials said that fully vaccinated people no longer needed to mask up, even indoors. The advice signified a sea change in American life, setting the stage for a national reopening that continues to gain momentum.

But that was before the spread of the Delta variant. Worried by a global surge in cases, the World Health Organization last week reiterated its longstanding recommendation that everyone — including the inoculated — wear masks to stem the spread of the virus.

On Monday, health officials in Los Angeles County followed suit, recommending that "everyone, regardless of vaccination status, wear masks indoors in public places as a precautionary measure."

Barbara Ferrer, the county's public health director, said the new recommendation was needed because of upticks in infections, a rise in cases due to the worrisome Delta variant, and persistently high numbers of unvaccinated residents, particularly children, Black and Latino residents and essential workers.

Roughly half of Los Angeles County residents are fully vaccinated, and about 60 percent have had at least one dose. While the number of positive tests is still below 1 percent in the county, the rate has been inching up, Dr. Ferrer added, and there has been a rise in the number of reinfections among residents who were infected before and did not get vaccinated.

To the extent that Los Angeles County has managed to control the pandemic, it has been because of a multilayered strategy that combined vaccinations with health restrictions aimed at curbing new infections, Dr. Ferrer said. Natural immunity among those already infected has also kept transmission low, she noted, but it is not clear how long natural immunity will last.

"We don't want to return to lockdown or more disruptive mandates here," Dr. Ferrer said. "We want to stay on the path we're on right now, which is keeping community transmission really low."

Health officials in Chicago and New York City said on Tuesday that they had no plans to revisit mask requirements. Officials at the Centers for Disease Control and Prevention declined to comment, but have not signaled any intention to revise or re-examine masking recommendations for those who are fully vaccinated.

"When the C.D.C. made the recommendation to quit masking, it didn't anticipate being in a situation where we might need to recommend masking again," said Angela Rasmussen, a research scientist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan in Canada.

"Nobody's going to want to do it. People are understandably accusing them of moving the goalposts."

But the Delta variant's trajectory outside the United States suggests that concerns are likely to intensify.

Countries in the Asia-Pacific region are now reimposing restrictions and stay-at-home orders as the variant drives new surges. Four Australian cites have reimposed lockdowns, and on Monday, the Malaysian government said nationwide stay-at-home orders would be extended indefinitely.

Even Israel — which has one of the highest vaccination rates in the world and is aggressively immunizing younger adolescents and teenagers who qualify — has reinstated masking requirements in public indoor spaces and at large public gatherings outdoors, after hundreds of new Covid-19 cases were detected in recent days, including among people who had received both doses of the Pfizer-BioNTech vaccine.

This is not the first time the world has been consumed by a more contagious variant of the coronavirus. The Alpha variant walloped Britain and brought the rest of Europe to a standstill earlier this year. In the United States, Alpha quickly became the dominant variant by late March, but the rapid pace of vaccination blunted its spread, sparing the nation a big surge in infections.

But Delta is thought to be even more fearsome. Much of what is known about the variant is based on its spread in India and Britain, but early evidence indicates that it is perhaps twice as contagious as the original virus and at least 20 percent more contagious than Alpha.

New York Times, By Roni Caryn Rabin, Apoorva Mandavilli and Shawn Hubler, June 29, 2021

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June 30, 2021

Voices4America Post Script. Are you vaccinated? I sure hope so. I also hope friends and family are vaccinated. Given the news about the Delta variant, I think you might want to wear a mask when indoors in public spaces. I do. This post summarizes where Delta is and recommended responses. #GetVaxed #MasksIndoors