(CNN) When President Joe Biden welcomed 1,000 essential workers and military personnel on the South Lawn this weekend to mark Independence Day, it fulfilled -- and even exceeded -- his prediction from March that July 4th gatherings this year would look more like they used to.
But underneath the jubilation was a gnawing concern that pockets of the United States remain in the grips of the pandemic, awash in cases of the highly transmissible Delta variant and populated with people who refuse to get vaccinated.
Even as a crowded South Lawn represented scenes of celebration across the country, concerns about the continuing spread of the virus remain strong inside the administration, which announced this week it would dispatch response teams across the US to communities where officials are worried about a potentially deadly combination: low vaccination rates and a significant presence of the highly transmissible form of the virus.
In private meetings, Biden has questioned advisers about the broader impact the highly contagious variant could have on the US, according to people present. He still receives a daily report on case rates, the number of deaths and the prevalence of variants. Officials have stressed that vaccinated people are safe, while those who are unvaccinated are the most at risk.
In a sign that the pandemic is far from over, officials also said the administration plans to extend the public health emergency declaration for the pandemic that former President Donald Trump announced in 2020 when it's due to expire this month.
And foreign travel to countries where the Delta variant is resurgent, including the United Kingdom, is still on hold as officials hope to avoid new cases coming in to the US, despite heightened pressure from foreign governments and the travel industry to open up. The rise of the Delta variant in the UK is the "primary reason" the US has not eased travel restrictions there, a senior health official told CNN. An administration official said their goal is to reopen international travel when it can be done safely but did not provide updates on when that's expected to happen. There are working groups between the US and other nations that are constantly evaluating the situation.
The competing impulses to celebrate progress against the virus while maintaining vigilance against further spread have colored the White House's approach to the second pandemic-era Fourth of July holiday.
Biden has come down overwhelmingly on the side of celebration, dispatching his wife, the vice president and other senior members of his administration to declare "America's Back Together" at parades, cookouts and fire stations across the country. Biden himself traveled Saturday to Traverse City, Michigan, where the annual Cherry Festival is underway again after officials canceled it last year.
There was some concern inside the White House about the optics of the July 4th party, with the Delta variant creeping its way across vulnerable populations of the US, according to one official. But there was never consideration of canceling the event. Guests were advised to get a test up to three days before the party, but won't be required to have been vaccinated. Masks for vaccinated people won't be required, in keeping with current guidelines from the US Centers for Disease Control and Prevention.
"Do we wish we were doing this having completely eradicated Covid? Yes, of course," said the official, who said there was never discussion about pulling the plug on the party. "We're moving ahead, with this event, with the initiatives, with trying to get people vaccinated. All of it."
On CNN's "State of the Union" on Sunday, Jeff Zients, the President's coronavirus response coordinator, defended the White House's decision not to require those who attend the first big bash to be vaccinated, saying that there's "very rigorous testing and screening protocols."
"I think most of these folks are vaccinated," Zients said, adding, "But at the end of the day, it's an individual choice, we hope all individuals make the right choice here and get vaccinated."
Biden hoped to proclaim this weekend that 70% of American adults had received at least one Covid-19 shot. But officials acknowledged more than a week ago the goal wouldn't be met as they struggle to convince still-resistant Americans to get shots. About 67% of Americans 18 and older had received at least one shot, according to CDC data reported Saturday.
For Biden and his aides, reality is setting in that getting the entire country vaccinated will be the work of his entire presidency -- and that pockets of the nation where vaccination rates remain low will continue to suffer outbreaks that hamper the nationwide recovery effort. Most US adults who plan to get vaccinated against Covid-19 have already done so, according to a Kaiser Family Foundation report released this week.
While they have declined to rule it out, officials do not currently expect Biden to set any more numerical goals when it comes to vaccinations, given the US has still not reached his last one and the pace of vaccinations has slowed significantly, according to people familiar with the discussions.
Instead, officials plan to simply push to get as many Americans vaccinated as soon as possible. A recent CNN analysis of the most recent vaccination data from the CDC finds that more than one in 10 Americans have missed their second shot. Officials say it is more vital than ever that Americans receive their second dose of the Pfizer or Moderna vaccine, since protection against the Delta strain is dramatically bolstered with the additional dose.
New questions have also emerged over whether mask mandates could return should the variant cause a spike in cases -- a possibility the White House has sought to publicly dispel after trumpeting the lifting of mask recommendations earlier this spring.
Dr. Rochelle Walensky, the director of the CDC, said Thursday the Delta variant of coronavirus remains a serious threat in the United States and could cause more Covid-19 cases, hospitalizations and deaths in unvaccinated communities -- especially those in the Southeast and Midwest.
"Looking state by state and county by county, it is clear that communities where people remain unvaccinated are communities that remain vulnerable," Walensky said.
She said as the Delta variant continues to spread in the US, the nation has seen a recent increase in its seven-day average of Covid-19 cases. On Wednesday, the CDC reported 14,875 new cases of Covid-19. The nation's current seven-day average is about 12,600 cases per day.
Biden said Friday he is not concerned about another widespread Covid outbreak -- but acknowledged he was wary of unvaccinated people catching the Delta variant at holiday gatherings.
"I am concerned that people who have not gotten vaccinated have the capacity to catch the variant and spread it to other people who have not been vaccinated," Biden told reporters at an event on the economy. "I am not concerned that there's going to be a major outbreak."
Biden reiterated his fears that "lives will be lost" should more people continue to resist getting vaccines.
"Don't think about yourself, think about your family. Think about those around you," he said. "That is what we should be thinking about today. The Fourth of July this year is different than the Fourth of July last year and it will be better next year."
In some ways, this weekend is the moment Biden predicted two months into his presidency, standing in the Cross Hall of the White House.
"If we do our part, if we do this together, by July the Fourth there's a good chance you, your families and friends will be able to get together in your backyard or in your neighborhood and have a cookout and a barbecue and celebrate Independence Day," Biden said in March, a long red carpet stretching behind him, setting a months-away goal for returning the country to normal.
Officials insist the relative normalcy of this year's holiday compared to the months spent under social distancing and mask restrictions was a signal Biden's strategy had worked.
"We made a lot of progress. I think we're much further along than anyone would have anticipated at this point," Zients told CNN's Dana Bash on Sunday, when asked why the administration fell short.
He added that the administration plans to "double down on our efforts to vaccinate millions of more Americans across July and August."
Much of that work has shifted to states where the combination of low vaccination rates and high caseloads have caused fears of backsliding.
"We are now going in the wrong direction yet again with Covid-19 infections here in the state of Arkansas," said Dr. Cam Patterson, chancellor at the University of Arkansas for Medical Sciences, during the state's weekly briefing last week.
Hoping to target the regional outbreaks, the White House said last week it was deploying response teams to conduct surge testing, provide therapeutics like monoclonal antibodies and deploy federal personnel to areas that need support staff for vaccinations.
The White House coronavirus team is spearheading the effort and officials expect the teams will help with everything from boosting testing, providing supplies and potentially increasing paid media efforts targeting regions where vaccinations are low.
Still, while the response teams are being sent to prop up communities, officials believe vaccinations are the number one way to stop the spread and recognize there could be a limit to their efforts.
Already, the administration has shifted its strategy from focusing on mass vaccination sites to more targeted efforts to get people shots. Health officials have narrowed their focus to young people in particular, who account for a large number of the still-unvaccinated. They also remain focused on minorities, whose vaccination rates lag behind the White population.
Recognizing the concern over the variant, the Biden administration flooded television networks with top federal health officials last week to address concerns ahead of the July 4th weekend.
And officials sought to balance what is undoubtedly a moment to mark progress against the virus with the nagging problem that large swaths of the country still appear resistant to vaccines.
"You can still celebrate at the same time as you get your message very, very clear: if you were vaccinated, you have a high degree of protection. If you are not, you should wear a mask, and you should think very seriously about getting vaccinated," Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said on Thursday.
"So, in so many respects, nothing has really changed," Fauci said. "We are celebrating as a country at the same time as we recognize the fact that we're in a serious situation for those who have not been vaccinated. And the message is: Get vaccinated."
This story has been updated with additional details Sunday.