The U.S. has reached a "landmark day" in the COVID-19 pandemic as 60% of American adults have gotten at least one dose of a coronavirus vaccine, the director of the U.S. Centers for Disease Control and Prevention said.In addition, more than 4.1 million young people ages 12 to 17 have received their first dose, Dr. Rochelle Walensky said."We need to continue to ensure vaccination coverage is uniform across the country," Walensky said Tuesday."This will require us to meet people where they are, to listen to their concerns, and to help people make informed decision about vaccination."While the news marks a positive step toward reaching herd immunity, many are grappling with the CDC's latest guidance on face masks.Several days after CDC said fully vaccinated Americans can -- for the most part -- ditch their masks, more places are changing their mask policies -- or scrapping them altogether.CVS pharmacy and Target said they will no longer require fully vaccinated guests to wear masks inside their stores unless mandated by local leaders, joining other businesses that have dropped mask mandates for those who have gotten their shots."Face coverings will continue to be strongly recommended for guests and team members who are not fully vaccinated," Target said in a statement. Unvaccinated CVS customers are asked to continue masking up.Washington, DC, Mayor Muriel Bowser said fully vaccinated people won't be required to wear masks anymore in many locations, with exceptions for schools, health care facilities and transportation hubs."If you're not vaccinated or not yet fully vaccinated, we need you to continue to protect yourselves," Bowser said Monday.And starting Wednesday, New York will adopt the CDC guidelines and not require masks or social distancing for fully vaccinated people, Gov. Andrew Cuomo said Monday.But experts are worried about the rapid changes and say that without verification systems, parts of the country are now having to rely on an honor system to ensure unvaccinated Americans are masking up -- a system that some say does not work."I say this respectfully to the CDC, but we really need to get back to a point where it's encouraging (people) to get vaccinated and more of that focus rather than celebrating our newfound freedoms," Mayor Quinton Lucas of Kansas City, Missouri, said."Because the honor system just ain't working here, I don't think it's going to work in a lot of parts in this country,"Now, local officials are worried about how to move forward, Lucas said."It creates these sort of challenges where, how does the store clerk check it? How does our health department actually enforce any rule at all? So, while I respect many of the jurisdictions that are trying to, I think, really have adherence to the CDC (guidance), it's a challenge for us," the mayor said.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Some state and local leaders hold onto masksOther leaders have not been as quick to ditch mask requirements.While Maryland Gov. Larry Hogan announced the end of the statewide mask mandate last week, Baltimore City health officials announced a local mandate would remain in place until at least 65% of adults in Baltimore have received at least one COVID-19 vaccine dose.In New Jersey, Gov. Phil Murphy signed an order Monday eliminating a mask requirement for outdoor public spaces but kept a masking requirement for indoor public spaces and workplaces."Outdoor environments pose a lesser risk of transmission of the virus than indoor settings, and lifting the indoor mask mandate at this time could lead to a rise in transmission among those not yet fully vaccinated, including children who are either not yet eligible or who have just recently become eligible," Murphy said in a statement."As we approach our vaccination target in the coming weeks, we expect to be able to safely lift the indoor mask requirement soon," he added.California also plans to keep its mask mandate for indoor activities in place for another month, officials said. The state's face covering rule will be dropped for fully vaccinated residents on June 15, Health and Human Services Secretary Dr. Mark Ghaly announced Monday."This four-week period will give Californians time to prepare for this change, while we continue the relentless focus on delivering vaccines, particularly to underserved communities and those that were hard hit throughout this pandemic," Ghaly said.The effort to get shots into arms continuesOne expert said she expects about 20% to 25% of Americans won't want to get a vaccine -- but says she hasn't given up on all of them yet."There's still a ground game that is being played, it's about going door to door, it's about getting trusted community leaders," emergency physician Dr. Megan Ranney said.For example, if people are directly offered a vaccine, they will often agree to get the shot, she said."If we do that, we will get a significant percentage of those folks who have not yet been vaccinated," Ranney added.The CDC is also asking businesses to help support workers to get vaccinated, Walensky said earlier this week."We are really asking the businesses to work with their workers to make sure that they have the paid time off to get themselves vaccinated so they can be safe," Walensky said.Expert: Pandemic won't end in U.S. until it ends globallyMeanwhile, President Joe Biden said Monday his administration would share millions more doses of COVID-19 vaccines with other countries -- in addition to the 60 million doses of the AstraZeneca vaccine he has already committed to sharing by July 4.The president said that the U.S. would share at least 20 million doses of COVID-19 vaccines by the end of next month, totaling 80 million doses that are set to be sent abroad.The additional 20 million doses will include Moderna, Pfizer and Johnson & Johnson vaccines as well as AstraZeneca, which has to be approved by federal regulators before being shipped overseas. That effort is underway."What they've announced today is really important," Dr. Tom Frieden, a former CDC director, told CNN on Monday. "This pandemic will not be over for the US until it's over globally."Biden also said that Monday's announcement was the latest effort by his administration to ramp up efforts abroad and work with other world leaders to end the pandemic and said he expected to announce progress on beating the pandemic overseas at the G7 summit in June.