(CNN)A maskless Memorial Day weekend is a huge deal. People are traveling, Covid-19 cases are down across most of the country and vaccines have made their way into millions of arms.
And while glimpses of normalcy are exciting to see, one health expert is warning that the millions of people who have not been vaccinated may pose high risks to each other.
People crowd the Santa Monica Pier in Santa Monica, California, on Saturday, May 29, 2021.
Dr. Leana Wen, a CNN medical analyst, said people who are fully vaccinated and are generally healthy "should feel very well protected."
But she offered a more critical insight on those who are not.
"Those who remain at risk are those who are unvaccinated," Wen told CNN on Saturday. "And that includes children who are not yet eligible to be vaccinated as well as adults who just have not been vaccinated yet."
She added that even though 40% of the country is fully vaccinated, the risk remains high because a large portion of the population still hasn't been inoculated. While the number of new Covid-19 cases have dropped significantly, that also means "the virus has fewer places to go."
"And so those people who are unvaccinated are now still at high risk because we do have more transmissible variants, and unfortunately those individuals who don't have immunity are not protected from these variants that can wreak a lot of havoc," Wen explained.
Motorcyclists wait for traffic along North Ocean Blvd. on May 29, 2021 in Myrtle Beach, South Carolina.
People who are severely immunocompromised and have received a vaccine may also potentially be at risk, she said.
As of Saturday, more than 167 million people in the US -- 50% of the total population -- have received at least one vaccine dose, and more than 134 million people are fully vaccinated, data from the US Centers for Disease Control and Prevention shows.
The current 7-day average of daily new cases in the US is 21,627, a more than 22% decrease from the previous week, according to the CDC.
"Go, get vaccinated, hit the beach. Real simple."
As people get out and about this long weekend, states are jumping at the opportunity to get more vaccine shots into arms.
New Jersey launched a new program, "Shots at the Shore," to incentivize people to take the vaccine.
People who head down to the Jersey shore will have the option to receive any of the three vaccines -- Moderna, Pfizer or Johnson & Johnson -- Gov. Phil Murphy said. Younger people ages 12 to 15 may take the Pfizer shot.
People ride along the boardwalk on the Jersey shore on May 27, 2021 in Wildwood, New Jersey.
Vaccination sites are set up in Pier Village, Sandy Hook, Long Branch, and Asbury Park from 9 a.m. to 3 a.m. on Memorial Day weekend, Murphy said.
New Jersey is one of 10 states that has reached and exceeded President Joe Biden's goal to vaccinate 70% of their populations by July 4.
Meanwhile, New York City was also slated to post buses at beaches and parks this Memorial Day weekend offering free Covid-19 vaccinations, Mayor Bill de Blasio said.
Buses were planned at Brighton Beach, the Rockaways, Brooklyn Bridge Park, Central Park and Governors Island, to name a few, the mayor said.
"We're going to go the extra mile, whatever it takes," said de Blasio. "You're going to see our vaccine buses out all over New York City the next few days.
"Go, get vaccinated, hit the beach. Real simple."
Photos: How Americans are spending their Memorial Day weekend
Photos: How Americans are spending their Memorial Day weekend
Michael Cosgrove, deputy chief of the Rose Tree Fire Company, unfurls an American flag before the start of Memorial Day services in Rose Tree, Pennsylvania, on Monday, May 31.
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Photos: How Americans are spending their Memorial Day weekend
Bugler David Bonczkiewicz plays with the honor guard Monday at the National Memorial Cemetery of Arizona.
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Photos: How Americans are spending their Memorial Day weekend
President Joe Biden delivers an address at Arlington National Cemetery on Monday. "We owe the honored dead a debt we can never fully repay," he said in his speech. "We owe them our whole souls. We owe them our full best efforts to perfect the union for which they died."
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Photos: How Americans are spending their Memorial Day weekend
Army Capt. Darren M. Cinatl touches the headstone of his friend Andrew Joseph Baddick at Arlington National Cemetery.
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Photos: How Americans are spending their Memorial Day weekend
New York Mayor Bill de Blasio speaks during the Intrepid Sea, Air & Space Museum's annual Memorial Day ceremony in New York.
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Photos: How Americans are spending their Memorial Day weekend
American flags are placed next to the headstones in Arlington National Cemetery.
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Photos: How Americans are spending their Memorial Day weekend
Veteran Tim Chambers salutes motorcyclists participating in the "Rolling to Remember" event in Washington, DC, on Sunday, May 30.
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Photos: How Americans are spending their Memorial Day weekend
People visit the Vietnam Veterans Memorial in Washington, DC, on Sunday.
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Photos: How Americans are spending their Memorial Day weekend
A boy makes his way through the aerial ropes course at Harpers Ferry Adventure Center in Hillsboro, Virginia, on Sunday.
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Photos: How Americans are spending their Memorial Day weekend
Fans watch the Indianapolis 500 auto race on Sunday. This year's event was billed as the most-attended sporting event since the pandemic's start, with the 135,000 available tickets quickly selling out.
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Photos: How Americans are spending their Memorial Day weekend
People dance on a boat in Chicago on Sunday.
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Photos: How Americans are spending their Memorial Day weekend
People visit the Coney Island boardwalk as rain falls in New York on Sunday.
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Photos: How Americans are spending their Memorial Day weekend
Hot-air balloons dominated the field Sunday in front of the National World War I Museum and Memorial in Kansas City, Missouri.
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Photos: How Americans are spending their Memorial Day weekend
People walk along the Santa Monica Pier in California on Saturday, May 29.
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Photos: How Americans are spending their Memorial Day weekend
Elias Loosen plants a flag Saturday as part of the War Memorial Center's Field of Flags community event in Milwaukee.
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Photos: How Americans are spending their Memorial Day weekend
Tubers make their way to the lower Salt River in Arizona on Saturday.
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Photos: How Americans are spending their Memorial Day weekend
Air Force veteran Larry Bustetter, left, and Army veteran Henry Knebel salute after placing flags at the Los Angeles National Cemetery on Saturday.
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Photos: How Americans are spending their Memorial Day weekend
Motorcyclists wait for traffic along North Ocean Boulevard in Myrtle Beach, South Carolina.
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Photos: How Americans are spending their Memorial Day weekend
People ride a roller coaster at the pier in Santa Monica, California, on Saturday.
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Photos: How Americans are spending their Memorial Day weekend
A large crowd gathers to watch a street performance in New York's Times Square on Saturday.
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Photos: How Americans are spending their Memorial Day weekend
People ride escalators at Atlanta's Hartsfield-Jackson International Airport on Friday, May 28.
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Photos: How Americans are spending their Memorial Day weekend
Volunteers place flags at the Iowa Veterans Cemetery in Adel, Iowa, on Friday.
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Photos: How Americans are spending their Memorial Day weekend
People enjoy the boardwalk Friday in Wildwood, New Jersey.
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Photos: How Americans are spending their Memorial Day weekend
Jacqueline Blair hangs ribbons on flags Friday at the Field of Honor in Idaho Falls, Idaho. A thousand flags will be on display at the Russ Freeman Park through Memorial Day.
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Photos: How Americans are spending their Memorial Day weekend
Travelers pass through the concourse Friday at Ronald Reagan Washington National Airport in Arlington, Virginia.
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Photos: How Americans are spending their Memorial Day weekend
Beachgoers watch as US Marine helicopters practice maneuvers Friday for an air and sea show in Miami Beach, Florida.
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Photos: How Americans are spending their Memorial Day weekend
A US soldier places a flag as part of the Flags In ceremony at Arlington National Cemetery on Thursday, May 27. More than 1,000 service members placed flags in front of more than 260,000 headstones.
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Photos: How Americans are spending their Memorial Day weekend
People ride along the boardwalk in Wildwood, New Jersey, on Thursday.
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Photos: How Americans are spending their Memorial Day weekend
Vehicles head east out of Los Angeles on Interstate 10 in Alhambra, California, on Thursday. More than 37 million people were expected to travel 50 miles or more from home between Thursday and Monday, according to AAA.
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Overall, nearly 294 million Covid-19 vaccine doses have been administered in the US, according to CDC data published Saturday.
Miami Beach mayor on tourist influx: "The virus is still here"
Travel was in the air this weekend, hitting a pandemic-era record of passengers on Friday. About 1.96 million people traveled through US airports, according to the Transportation Security Administration.
"We're creeping up to 2 million. Please wear your mask, respect TSA/airport/airline crew, arrive early & pack your patience!" a spokesperson for the TSA tweeted.
People relax on the sand during the Memorial Day Hyundai Air and Sea Show in Miami Beach, Florida on May 29, 2021.
Some of those travelers headed to Miami Beach, Florida, where Mayor Dan Gelber expressed concern over the influx of tourists to his city this Memorial Day weekend.
Gelber said one of the problems is that "we're one of the few places open, but we're also a very attractive destination. So simply, too many people are coming."
"The virus is still here," he reminded everyone when speaking with CNN's Kate Bolduan on Friday. "The volume of people that have been coming here is very unprecedented, and some who are coming are looking to sort of act out."
The mayor said there will be "an enormous saturation of police officers" on patrol over the long weekend.
