The total number of Covid-19 diagnoses in the U.S. hit 19 million on Sunday, as millions of Americans were expected to travel over the Christmas weekend.
That increased travel is now spreading concern of a further surge in infections at a time when hospitals in a number of states are filling up with Covid patients.
More than 117,000 people are currently hospitalized with Covid-19 nationwide, according to the Covid Tracking Project.
In addition -- despite the relatively slow rollout of vaccines nationwide that began earlier this month -- every state except for Hawaii is seeing uncontrolled spread of the virus, according to Covidexitstrategy.org.
Assistant Secretary for Health and Human Services Admiral Brett Giroir told "Fox News Sunday," however, that "we really have to wait and see" how much travel during the holidays adds to a rise in cases over the coming weeks.
"We know the actual physical act of traveling in airplanes, for example, can be quite safe, because of the air purification systems. What we really worry about is the mingling of different bubbles once you get to your destination," Giroir said, when asked about data showing that around a million people per day were taking flights in the days leading up to Christmas.
Giroir added that over Thanksgiving, the nation "saw a mixed picture" on the spread of the virus, noting that cases went down in the Midwest and in the northern plains in the weeks following the November holiday.
But the virus has been rapidly spreading throughout the nation over the past couple of months, with 226,274 cases reported for Saturday alone, according to Johns Hopkins.
At the same time that the nation is seeing a record rise in cases, vaccines by both Moderna (MRNA) - Get Report and Pfizer (PFE) - Get Report and BioNTech (BNTX) - Get Report began getting distributed throughout the country in the past several weeks.
Giroir said that a total of 20 million vaccines will be distributed by the first week in January, with tens of millions more on the way in the next couple of months.
Each of the vaccines currently available by emergency authorization requires two doses to fully project against developing severe disease.
Giroir added that, "With the current contracts, even with just the vaccines we have right now, we still expect that any American who wants a vaccine can be vaccinated by June."
Nearly 332,000 in the U.S. have died so far from the disease, according to the Johns Hopkins University disease tracker.