"First and foremost, if you are unvaccinated, we would recommend not traveling," Centers for Disease Control and Prevention Director Dr. Rochelle Walensky said during a White House COVID-19 briefing Tuesday.
Holidays, which often entail traveling and large gatherings, have proven to be a catalyst of rapid COVID-19 spread across the country.
Last year, in the weeks prior to Labor Day, the country was experiencing a steady decline in COVID-19 cases, with the national daily case average falling to approximately 38,000.
However, the late summer holiday weekend set the stage for the country's most significant viral surge of the pandemic. Between mid-September and Thanksgiving, the nation's daily case average rose by more than 400%, followed by a record-setting influx of hospitalizations and deaths.
CDC COVID-19 Transmission Levels by U.S. CountyMap not displaying correctly? Click here to open in a new window.
The country's current average is now more than 100,000 daily cases higher than it was a year ago, with the U.S. reporting more than 153,000 new cases each day, following weeks of increasing metrics. Since the Fourth of July, COVID-19-related infections, hospitalizations and deaths surged to levels not seen since last winter.
"As we head into Labor Day, we should all be concerned about history repeating itself. High or intense transmission around most of the country combined with population mobility with limited masking and social distancing has been a consistent predictor of major surges," said Dr. John Brownstein, an epidemiologist at Boston Children's Hospital and an ABC News contributor.
Experts are warning that although vaccination rates may help partially blunt the impact of a potential Labor Day holiday surge this year, and protect those who are inoculated against severe disease, the country could still be at-risk for the unwanted impacts of unmitigated spread.
"While we now have widespread vaccine uptake, we still have large segments of the population that remain fertile ground for the virus to spread, including our children," Brownstein said.
With more than 47% of Americans still not fully vaccinated, there is concern that an increase in infections could push already struggling health systems in states with low vaccination rates to the brink, Brownstein added.
Seven states -- Alabama, Arkansas, Florida, Georgia, Kentucky, Mississippi and Texas -- have intensive care units about 90% or more filled, and nationally, nearly 8 in 10 staffed adult ICU beds are occupied by COVID or non-COVID patients.
A recent report published by the CDC found unvaccinated people were five times more likely to get COVID-19 than vaccinated people -- and 29 times more likely to be hospitalized for their infections, and ICU bed capacity remains tight in several states with low vaccination rates.
"We need more individuals to step up, as people across the country prepare for Labor Day weekend," White House COVID-19 response coordinator Jeff Zients said during Tuesday's briefing. "It's critical that being vaccinated is part of their pre-holiday checklist."
Walensky added that while fully vaccinated people can feel comfortable traveling, with the added protection of masks, it is important that they take into consideration the risks of COVID-19 infection, given the high transmissibility of the delta variant, prior to deciding whether to or not to travel.
It is also essential, said Walensky, that those who choose to celebrate the weekend holiday take precautions in order to keep themselves safe, such as gathering outside and with others who are vaccinated.
"Throughout the pandemic, we have seen that the vast majority of transmission takes place among unvaccinated people in closed, indoor settings," she warned.
Further, Walensky said, while inside, wear masks to mitigate the spread of the disease.
The warnings come at yet another critical turning point in the pandemic, with infection rates still on the rise driven by the highly contagious delta variant.
Every state in the country is now experiencing high community transmission and nearly 103,000 Americans are currently hospitalized with the virus -- one of the highest numbers of patients receiving care in seven months. An average of 1,000 Americans are also currently losing their lives each day from the virus.
Also, pediatric COVID-19 infections and hospitalizations are reaching their highest point of the pandemic, as many unvaccinated children fall victim to the virus.
"With children returning to in-person school after Labor Day, health officials stress it is critical to act cautiously and responsibly in order to reduce transmission," Brownstein said.
In the last week alone, nearly 204,000 children have tested positive for COVID-19, marking the second highest week on record, according to the American Academy of Pediatrics and the Children's Hospital Association.
Since the Fourth of July, the rate of child hospital admissions per capita has grown sevenfold, coinciding with the rapid spread of the highly infectious delta variant. Further, hospitalization rates among unvaccinated adolescents were 10 times the rate of those fully vaccinated, according to a newly released CDC study.
"It will be critical for eligible Americans who are still unvaccinated to get the shot, and protect those who are still vulnerable," Brownstein said.