The agency on Thursday announced that fully vaccinated individuals can ditch their masks in most settings, but some public health experts raised concerns about how to prove vaccination. The CDC on Thursday announced that fully vaccinated individuals can ditch their masks and social distancing indoors and outdoors in most settings. Masks must still be worn “where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance,” according to the guidance. There are also exceptions for correctional facilities and homeless shelters, and people who are immune compromised should speak to their doctors before abandoning their masks. CDC Director Rochelle Walensky cited declining coronavirus cases, increasing vaccine supply and emerging data on the performance of vaccines as reasons for the guidance change. States including North Carolina, Michigan, Nevada, Oregon, Pennsylvania, Minnesota, Kentucky, Washington and Kansas all announced changes to their mandates following the CDC guidance. “Today is a great day,” North Carolina Gov. Roy Cooper tweeted Thursday as he lifted most mandatory mask requirements for his state. “But the work is not yet done and people getting vaccinated will get it done. The CDC’s guidance affirms that getting vaccinated is the way through this. We can take this step today because the science shows our focus on getting people vaccinated is working.” But some public health experts were left with questions and concerns about unvaccinated people abandoning their masks. According to CDC data, just over 36% of Americans are fully vaccinated. “On one hand, people may feel more incentivized to get the vaccine if they see that by getting the vaccine, they no longer have to wear a mask and can resume pre-pandemic activities,” Rupali J. Limaye of Johns Hopkins University said in a statement. “On the other hand, it may not be enough of an incentive to get the vaccine, and may signal to people that they can go maskless while being unvaccinated, as there is no way to know who is vaccinated and who is not.” “This could lead to a situation where those that are unvaccinated may be maskless in settings where there are other unvaccinated individuals, leading to higher risk of exposure,” she continued. Leana Wen, a visiting professor at George Washington University Milken Institute School of Public Health, wrote in an opinion piece for The Washington Post that the CDC “has gone from one extreme to the other, from over-caution to throwing caution to the wind.” She said that the new guidance “would be very welcome if not for one big problem: There is no concurrent requirement for proof of vaccination.” Leading infectious disease expert Anthony Fauci acknowledged that “you’re going to be depending on people being honest enough to say whether they were vaccinated or not and responsible enough to be wearing … a mask, not only for their own protection but also for the protection of others.” The federal government has repeatedly said it will not require vaccine passports or similar certifications. But beyond concerns about putting trust in the public, questions swirled on the guidance. Could a fully vaccinated workforce go back to the office without wearing masks and social distancing? Should private businesses like grocery stores that currently implement mask mandates follow CDC guidance and shed the requirements for vaccinated people, or would that risk workers facing retaliation for implementing vaccine policing? The United Food and Commercial Workers, America’s largest union for front-line retail and grocery workers, criticized the guidance, calling it “confusing” and accusing the agency of failing “to consider how it will impact essential workers who face frequent exposure to individuals who are not vaccinated and refuse to wear masks.” Fauci told CNN that while some businesses might choose to require proof of vaccination, he does not suggest policing behaviors. “People feel very put upon if you are essentially judging them on the basis of whether they have been vaccinated,” Fauci added. “I think there is going to be a pushback against questioning somebody when they walk in.” And what about parents who are vaccinated who have young children who aren’t eligible for the shot yet – how will they convince the youngsters to keep their masks on as more and more people go without them? Fauci told CNN that children still need to wear masks “when they’re out there playing with their friends and, you know, particularly in an indoor situation.” Elementary school-aged children likely won’t be vaccinated until the end of the year, according to Fauci. That leaves parents to navigate starting the school year without vaccinations for their youngest kids, and both Walensky and Fauci have supported the idea of all schools holding in-person education five days a week by the fall.