(CNN) People can celebrate the Fourth of July as long as they take the appropriate precautions, Dr. Anthony Fauci said Thursday, while urging people to "get vaccinated."
Asked whether it was appropriate to hold a mass gathering and fireworks display on the National Mall in Washington, DC, as the pandemic continues, White House coronavirus response coordinator Jeff Zients said it was.
"It's an appropriate time to step back and celebrate the progress we've made," Zients said at a White House briefing.
"You can still celebrate at the same time as you get your message very, very clear," Fauci agreed.
"That is, 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," added Fauci, the director of the National Institute of Allergy and Infectious Diseases.
"So, in so many respects, nothing has really changed. 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."
Holiday celebrations nonwithstanding, the Delta variant of the coronavirus continues to spread and the nation has seen an increase in its seven-day average of Covid-19 cases, the director of the Centers for Disease Control and Prevention said Thursday.
The nation's current seven-day average, covering June 23-29, is 12,609 cases per day, a 10% increase from the previous seven-day average of 11,428, covering June 16-22, said director Dr. Rochelle Walensky during a virtual White House briefing.
And while the seven-day average has decreased 95% since January 10, Walensky said the Delta variant remains a serious threat and could cause more Covid-19 cases, hospitalizations and deaths in unvaccinated communities, especially those in the Southeast and Midwest.
"The Delta variant is predicted to be the second most prevalent variant in the United States, and I expect that in the coming weeks, it will eclipse the Alpha variant," Walensky said.
The Alpha variant, also known as B.1.1.7, was first seen in Britain. The Delta variant, known as B.1.617.2, was first seen in India.
Across the country, Walensky said, communities with low vaccination coverage remain vulnerable, especially due to the spread of the "hyper-transmissible Delta variant."
"Currently, approximately 1,000 counties in the United States have vaccination coverage of less than 30%. These communities, primarily in the Southeast and Midwest, are our most vulnerable," Walensky said.
"In some of these areas, we are already seeing increasing rates of disease. As the Delta variant continues to spread across the country, we expect to see increased transmissions in these communities, unless we can vaccinate more people now."
As concerns about the Delta variant grow, the Biden administration announced Thursday that it is deploying response teams across the US to areas with high spread of the virus, a White House official told CNN.
These teams will go into communities where officials are worried about a potentially deadly combination: low vaccination rates and a significant presence of the highly infectious Delta variant. The teams will be composed of officials from the CDC, the Department of Health and Human Services and the Federal Emergency Management Agency.
These response teams will help to provide more testing, deploy federal personnel to areas that need support staff for vaccinations and provide therapeutics such as monoclonal antibodies.
However, officials believe vaccinations are the top way to stop the spread and recognize there could be a limit to their efforts. 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.
"We want to be as clear as possible," White House press secretary Jen Psaki said Thursday. "If you have been vaccinated, the message we're conveying is you're safe ... if you are not yet vaccinated, you are not safe and protected. That's why you should go get vaccinated. It's not more complicated than that in some regards."
With uneven vaccination rates across the US and the Delta variant now spotted in all 50 states, one health expert says the federal government's mask guidance needs to be more focused.
"Part of the problem is that the CDC is trying to use a one-size-fits-all recommendation for the country rather than being a bit more surgical in identifying hot spot areas where transmission is accelerating," Dr. Peter Hotez told CNN's Jake Tapper on Wednesday.
Hotez, the dean of the National School of Tropical Medicine at Baylor College of Medicine, noted people in areas where vaccination rates are low and the virus is more prevalent may not want to do the same activities as people who live in areas where vaccination rates are high and the virus is more contained.
Alabama, Arkansas, Louisiana, Mississippi, and Wyoming have the lowest vaccination rates in the country, with less than 35% of their total population fully vaccinated, according to the most recent data from the CDC.
Connecticut, Maine, Massachusetts, and Vermont have fully vaccinated more than 60% of their total population, the data shows.
The CDC's current mask guidance, which says fully vaccinated people do not need to wear a mask indoors or outdoors, needs to be more specific with the Delta variant in mind, Hotez said.
"I think that's what we need from the CDC is to be able to cut it a little finer, come up with ... a force of infection map that combines those two variables: the low vaccination rates, high Delta. Those places are at great risk for lots of transmission, including some vaccinated individuals who will have breakthrough infections."
Breakthrough infections, while rare, happen when vaccinated people contract Covid-19. A recent CDC study showed that when vaccinated people are infected, they experience milder illness than unvaccinated people.
Fauci said Tuesday he doesn't expect the CDC to make changes to its mask guidance but warned Americans must take the Delta variant seriously.
Fauci noted that vaccines make Covid-19 case surges "entirely avoidable, entirely preventable."
Children under 12 are another vulnerable group in the face of Covid-19 variants because federal officials have not cleared them to receive a vaccine.
Dr. Yvonne Maldonado, chair of the American Academy of Pediatrics' Committee on Infectious Diseases, told CNN on Wednesday that children not yet vaccinated should still mask up, even if they're around fully vaccinated people.
"The vast majority of new infections are occurring among unvaccinated individuals," Maldonado said in an email to CNN. "For these unvaccinated children, masking, distancing and avoiding large crowds is recommended."
Hotez echoed Maldonado's stance on children wearing masks.
"I would say right now, if your kids are old enough to wear masks, then they should when they're indoors, at least until we can get our arms around this Delta variant," said Hotez, noting that parents should take their area's vaccination rate and variant levels into account.
Federal health officials plan to analyze vaccine data for children younger than 12 in the upcoming fall or winter, said Dr. Peter Marks, who heads the US Food and Drug Administration's Center for Biologics Evaluation and Research.
Former US Surgeon General Dr. Jerome Adams said Thursday there are three big issues when it comes to vaccine hesitancy in the United States: misinformation, mistrust and a misperception that access is no longer an issue for certain US communities.
"There are three big 'mis-es' that we have in terms of vaccine hesitancy," Adams told CNN's Erica Hill on "New Day."
"One is misinformation. Two is mistrust. And the third is a misperception that access still isn't an issue for many communities. For Black and Brown communities, for rural communities, access remains a problem."
Adams told Hill that "mistrust is huge, misinformation, unfortunately, is all over the place and we need the federal government, I'm going to say this today in my testimony, to really have a full-court press on PSAs, on community engagement to combat that constant stream of misinformation."
Adams was testifying Thursday at a House Select Subcommittee on the Coronavirus Crisis hearing on vaccine hesitancy.
African American communities have "a good reason for mistrust," he said, and Hispanic communities are afraid they will face immigration issues if they come in and get vaccinated.
Many rural communities have been put off by the politicization of the pandemic, Adams said, "and everyone's responsible for that." He said he has never heard someone say that they wouldn't get vaccinated because they're a Republican; rather, they say they don't trust the government or medical institutions.
As of Thursday, 47% of the total US population is fully vaccinated, CDC data showed. In the past seven days, the US averaged 26.6 new Covid-19 cases per 100,000 people.
While still lagging, vaccination coverage among young adults is improving, CDC data shows. Over the past two weeks, the 18-24 age group made up 12.6% of those becoming fully vaccinated, the CDC said.
Meanwhile, a new study is highlighting the importance of vaccines and the protection they offer. The study examined nearly 4,000 frontline health and emergency workers shows that the Pfizer/BioNTech and Moderna Covid-19 vaccines were 91% effective in preventing infection after two doses and 81% effective after a single dose.
"If you get vaccinated, about 90% of the time you're not going to get COVID-19," Dr. Jeff Burgess of the University of Arizona, which participated in the study, said in a statement. "Even if you do get it, there will be less of the virus in you and your illness is likely to be much milder."
The team, led by CDC epidemiologist Mark Thompson, studied 3,975 health care personnel, first responders, and other essential and frontline workers.
The virus was detected in 204 participants, of whom five were fully vaccinated, 11 partially vaccinated and 156 unvaccinated, the report in the New England Journal of Medicine said.
Those who were vaccinated and got infected anyway had less virus in their bodies -- 40% less, researchers added. Vaccinated people were 58% less likely to have fevers. "And the duration of illness was shorter, with 2.3 fewer days spent sick in bed," the researchers said.