The spread of the delta coronavirus variant—mostly among unvaccinated individuals—has led Los Angeles County and several other localities across the nation to restore mandates requiring both vaccinated and unvaccinated people to wear masks in some settings.

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Los Angeles, DeKalb counties strengthen mass requirements

On Thursday, Los Angeles County announced that on Saturday, July 17, it would reimplement a local mandate that requires everyone—regardless of their vaccination status—to wear masks in indoor spaces, the Washington Post reports.

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In their announcement, officials said they reinstituted the mandate in part because evidence indicates that a "very small number of fully vaccinated individuals can become infected and may be able to infect others," the Post reports. The prior mandate had been lifted on June 15, when the state removed most coronavirus-related restrictions, although officials later that month strongly encouraged people to wear masks.

According to officials, the announcement comes in response to a surge in Covid-19 cases driven by the delta variant, which now accounts for half of new coronavirus infections in the United States. Coronavirus case rates have more than doubled since late June. Daily deaths related to Covid-19, however, have remained under 300 on average through July, in part because elderly individuals who are at highest risk from the coronavirus are disproportionately likely to be vaccinated, the Post reports.

In Los Angeles County, officials said they decided to reimpose the mandate once the locality reported seven consecutive days of more than 1,000 new coronavirus infections, which they said constitutes "substantial transmission." Daily test positivity also increased, going from around 0.5% on June 15 to 3.75%. In addition, according to officials, Covid-19 hospitalizations rose from 275 on July 7 to 400 on July 14.

Officials added that of the coronavirus samples genetically tested between June 27 and July 3, around 70% were associated with the delta variant.

"Masking indoors must again become a normal practice by all, regardless of vaccination status, so that we can stop the trends and level of transmission we are currently seeing," Los Angeles County officials said. "We expect to keep this order in place until we begin to see improvements in our community transmission of Covid-19."

Other counties in California, including Sacramento and Yolo, haven't implemented mandates but are now strongly encouraging people to wear masks indoors.

Similarly, the Southern Nevada Health District, the public health authority for the city of Las Vegas, on Friday recommended that "both unvaccinated and vaccinated people wear masks in crowded indoor public places where they may have contact with others who are not fully vaccinated."

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Separately, DeKalb County in Georgia announced last week it would institute a mask mandate for all schools and buses, reversing its plan announced last month that masks would be optional. The mandate applies to everyone indoors or on a school bus, regardless of vaccination status, though the county said it would assess ways to identify people who have been vaccinated and "re-evaluate optional mask wearing."

During a school board meeting last week, a district official with DeKalb County said wearing masks "would be in the best interest" of everyone once classes begin due to the increase in Covid-19 cases in Georgia, a state where just 37% of people have been fully vaccinated, the Atlanta Journal-Constitution reports.

Do mask mandates need to make a comeback?

While CDC guidance indicates fully vaccinated people can go without masks in most situations, the agency has said localities should adopt—and residents should abide by—stricter rules depending on conditions in their area.

CDC's guidance differs from that of experts from World Health Organization (WHO), who in June said fully vaccinated people should continue wearing masks and maintaining social distance to combat the spread of the delta variant. At the time, CDC Director Rochelle Walensky said CDC's guidance would not change in response to WHO's announcement.

Other public health experts suggested that it's time to revisit CDC's recommendations. For instance, former surgeon general Jerome Adams said on Twitter Saturday that "instead of vax it OR mask it, the emerging data suggests CDC should be advising to vax it AND mask it in areas with [rising] cases and positivity—until we see numbers going back down again."

Adams added that "CDC was well intended" when it advised that masking was no longer necessary for vaccinated individuals, "but the message was misinterpreted, premature, [and] wrong. Let's fix it."

But the current surgeon general, Vivek Murthy, argued that Los Angeles's move actually shows CDC's recommendations are working as intended. "I think the CDC's guidance around masks was intended actually to give flexibility to individuals and to localities," he told CNN.

Murthy added, "So when you see places like L.A. County and other parts of the country, where you see counties making decisions about masks that may be different from other counties, that's OK. They're doing that based on what's happening in their communities, based on vaccination rates and case counts." (Schnell, The Hill, 7/19; Williams, The Hill, 7/17; Lonas, The Hill, 7/17; Nirappil, Washington Post, 7/16; Weber/Antczak, ABC News, 7/15; Hubler/Smith, New York Times, 7/16; Dixon, Atlanta Journal-Constitution, 7/13)