For anyone who loves freedom and hates mask mandates or remote learning, Dr. Jerome Adams has a blunt message: Get vaccinated.

"More mitigation is coming. Whether it's masking, or whether it's closures or whether it's your kids having to return to virtual learning, that is coming," the Trump administration surgeon general told CBS' "Face the Nation" on Sunday.

"And it's coming because this pandemic is spiraling out of control yet again. And it's spiraling out of control because we don't have enough people vaccinated."

As of Sunday, only 49.1% of Americans have been fully vaccinated, according to the U.S. Centers for Disease Control and Prevention.

That's nowhere near enough vaccinations to stop the spread of the Delta variant, the most contagious strain of novel coronavirus ever identified.

In 48 states, the rate of new COVID-19 cases this past week jumped by at least 10% compared to the previous week, according to data from Johns Hopkins University.

In 34 of those states, the rate of new cases increased by more than 50%.

Hospitals are filling up again with COVID-19 patients -- except now, patients are younger than before, said doctors in Alabama, Mississippi, Florida and Missouri.

"The thing that's making this possible is the fact that we are dealing with the most transmissible version of Covid-19 that we've seen to date," current U.S. Surgeon General Dr. Vivek Murthy said.

So eligible Americans who want to prevent more mask mandates, business closures and a return to remote learning need to do their part and get vaccinated, said Adams, the Trump administration official.

"It's going to help every single American enjoy the freedoms that we want to return to," he said.

Immunocompromised people might be the first to get an extra dose

The COVID-19 vaccines used in the U.S. don't have any coronavirus in them, but they do require an immune system response to work.

So millions of Americans who are immunocompromised or take drugs that suppress the immune system might not get as much help from a vaccine as others do.

While there's been much speculation as to whether (or when) booster shots might be needed, the CDC and the U.S. Food and Drug Administration said this month that "Americans who have been fully vaccinated do not need a booster shot at this time."

But that could change as the data evolves, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

If a booster dose of vaccine is needed, people with suppressed immune systems might be the first to get one, Fauci told CNN on Sunday.

Those with suppressed immune systems can include transplant patients, those undergoing cancer chemotherapy, people with autoimmune diseases and those who are taking immune-suppressing drugs, Fauci said.

Like with many other vaccines, a small fraction of vaccinated people have gotten breakthrough infections.

But more than 97% of those hospitalized with COVID-19 are unvaccinated, CDC Director Dr. Rochelle Walensky said last week.

Within the tiny percentage of US hospitalized COVID-19 patients who were fully vaccinated, a study found 44% of them were immunocompromised people.

The CDC and the FDA are "exploring multiple options" for how to make a third dose of COVID-19 vaccine possible for immunocompromised people if needed, according to a statement Friday.

"Emerging data show there is an enhanced antibody response after an additional dose of mRNA COVID-19 vaccine in some immunocompromised people," the CDC said in a statement to CNN on Friday.

"While early data show some potential benefit to administering an additional dose, more evidence is needed to determine safety and effectiveness in immunocompromised people."

Those who are immunocompromised and vaccinated against Covid-19 might still want to keep wearing masks, Murthy said.

Surging COVID-19 numbers

In California, San Diego County and Los Angeles County both reported their highest number of cases since February, and hospitalizations in LA County have more than doubled in two weeks.

In Florida, state health data shows that new case positivity nearly doubled in two weeks, from 7.8% the week of July 2 to 15.1%.

And Louisiana now has the highest increase in cases per capita in the U.S., state officials said Friday.

"We know that more than 80% of these are the Delta variant -- that is what's causing this surge," Gov. John Bel Edwards said.

"And what's enabling the surge is a very low percentage of people who have been vaccinated."

In the rare case that a fully vaccinated person later gets infected, that infection will likely result in mild or no symptoms at all, Murthy said.

"If you do get a breakthrough infection -- which itself will be unusual -- it will be more likely to be mild or asymptomatic," the surgeon general said.

Vaccines offered at a music festival

As the rate of vaccination plummets in Florida, the rate of new COVID-19 infections has soared.

The state reported 73,199 new COVID-19 cases this past week -- up from 45,603 the previous week, according to data from the Florida Department of Health.

And the number of new vaccinations dropped by more than two-thirds over the past few months, from more than 769,000 doses given the week of May 14 to around 245,000 this past week.

Miami-Dade County Mayor Daniella Levine Cava urged concertgoers at the three-day Rolling Loud Festival this weekend to help slow the spread.

The vaccine site was set up in conjunction with the state Department of Health and will offer both Pfizer and Johnson & Johnson vaccines until midnight Sunday, according to the county's website.

"Our community is experiencing a dangerous spike in COVID cases," the mayor tweeted, "and if you aren't vaccinated, you can get the shot at a Rolling Loud vaccine pop-up all weekend."