(CNN) — Expectations the United States would find itself returning to pre-pandemic normalcy this summer are quickly giving way to the realities of a prolonged fight against Covid-19, as all 50 states see a rise in infections.

And health officials nationwide are taking note.

“If you are unvaccinated, the risk is incredibly high — and maybe in some areas higher than it’s ever been,” said Dr. Craig Spencer, director of global health in emergency medicine at Columbia University Medical Center.

“Because there are not mask mandates, people are enjoying this wonderful return of summer and are a little more carefree and lackadaisical and making it more possible that you could be exposed,” Spencer told CNN Friday.

Indeed, the number of people traveling by air set a pandemic-era record Friday, with nearly 2.2 million people screened at US airports, a spokesperson for the Transportation Security Administration said, adding an admonition: “#MaskUp.”

Meantime, vaccinated people should “continue to be smart,” but are very unlikely to get sick, be hospitalized or die of Covid-19, Spencer said.

How the pandemic affects vaccinated and unvaccinated individuals differently is being demonstrated in hospitals nationwide, as local health officials report an overwhelming majority of hospitalizations from Covid-19 among those who have not yet been fully vaccinated.

Roughly 48.4% of the US population is fully vaccinated, according to the latest data from the US Centers for Disease Control and Prevention. But the pace of vaccinations over a seven-day average has declined 13% from the prior week.

Among those states that have fully vaccinated less than half its residents, the average Covid-19 case rate was 11 new cases per 100,000 people last week, compared to 4 per 100,000 among states that have fully vaccinated more than half its residents, according to a CNN analysis of data from Johns Hopkins University.

Canada has surpassed the US in the percentage of fully vaccinated people 12 years and older, according to data from the countries’ governments. So far, 16,612,850 Canadians, or 50.04%, have been fully vaccinated, compared to 160,686,378 or 48.4% of Americans.

‘I don’t think we’ve seen the worst of it’

Local officials are continuing to sound the alarm about the increase in cases, particularly among those unvaccinated. Twenty states have fully vaccinated more than half of their residents, according to the CDC, but health care facility resources are being stretched in states with fewer vaccinations.

Only a fourth of residents in Mobile County, Alabama, are fully vaccinated, Commissioner Merceria Ludgood said at a news conference Friday. And now the county is seeing a massive increase in hospitalizations, according to Dr. Laura Cepeda, chief medical officer of the Mobile County Health Department, who said there’s been a 400% increase in hospitalizations in the last month.

Ludgood said she finds it “frustrating that once again we find ourselves gathering to sound the alarm” about the rise in cases.

Mayor Sandy Stimpson encouraged those who have gotten the shots to talk with their loved ones and neighbors.

“Today we have sports heroes, we have rock stars, we have movie stars, coaches encouraging people all across this country to get vaccinated,” Stimpson said. “But if you’ve been vaccinated, don’t underestimate your ability to reach out to someone and encourage them to do it. You may be that person to convince them that this is the right thing to do.”

Katie Towns, acting director of the Springfield-Greene County Health Department in Missouri told CNN Friday the department is requesting an alternative care site and staff from the state to address the growing number of Covid-19 cases and hospitalizations, saying, “It’s at a level that we’ve not seen before,”

“Most striking is the demographic and age,” she said of Covid-19 patients. “The illness has really shifted from being an older population … to being ages 20, 30, 40 years old in the hospital and needing ICU care and oxygen.”

Towns said “almost all” patients in the hospital are unvaccinated, and hospitals and health officials are projecting an increase in numbers following the Fourth of July holiday.

“I don’t think we’ve seen the worst of it,” Towns said when asked where the county stands with fighting the pandemic.

Louisiana Gov. John Bel Edwards said on Friday that since February, 97% of cases and deaths related to Covid-19 are of those who are not fully vaccinated.

The return of mask guidelines

But even in areas with higher rates of vaccination, officials are beginning to reinstitute safety protocols such as mask mandates to try and curb the spread.

Health authorities in the San Francisco Bay Area Friday announced they are recommending everyone wear masks indoors. That followed news this week from Los Angeles County, which will reinstate its indoor mask mandate Saturday night for both vaccinated and unvaccinated people.

George Metsos, owner of Patys Restaurant in Los Angeles, told CNN the mask mandates have been confusing, and the changing guidance doesn’t help.

“They say follow the science. Well, they said don’t wear masks if you’re vaccinated. Now put the mask on if you’re vaccinated,” Metsos said. “I need to protect my customers, I need to protect my employees and I have to follow the rules, but I’m very in touch with the American public: They’re very frustrated.”

Amid growing concern, local authorities “do have the discretion of going that extra mile or going the extra step it takes to make sure that the spread of this virus is really contained,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told NBC Nightly News. “And they do that by saying that everyone should wear a mask.”

Unvaccinated health care workers are causing staffing issues

While health officials have preached the need for Americans to get vaccines, one industry is also facing a growing crisis with unvaccinated workers: health care.

The University of Florida Health Jacksonville hospital, for example, is going through staffing issues due to unvaccinated staff and is seeing an uptick in hospitalizations due to Covid-19, according to Chad Neilsen, director of infection prevention.

Staffing at the hospital — it has seen a 50% increase in Covid-19 admissions in the last two weeks — is becoming a big issue, Neilsen noted, as unvaccinated staff are being exposed to and getting Covid-19 in addition to undergoing burnout. There is only around 52% vaccine compliance among employees at UF Health Jacksonville, according to the director.

“Unvaccinated employees seem to be taking longer to recover and longer to return back to work,” Neilsen said, as the hospital is considering pausing elective surgeries.

Only 56% of health care workers in nursing homes are fully vaccinated, according to an analysis from AARP, which says only one in five nursing homes hit the industry target of having 75% of staff fully vaccinated.

At a national level, many more residents than staff are fully vaccinated, per the analysis. While the number of deaths at nursing homes dropped significantly after the vaccine rollout, AARP attributed a third of all US Covid-19 deaths during the pandemic to residents and staff at nursing homes and long-term care facilities.

The Association of American Medical Colleges on Friday urged its member institutions to require Covid-19 vaccinations for employees to protect patients and health care personnel, as the Delta variant circulates.

“Across the country, we are seeing increasing evidence that those currently unvaccinated continue to be at high risk of acquiring Covid-19 and are the overwhelming majority of new hospitalizations,” AAMC President Dr. David Sorkin said Friday.

“Yet, we have tragically lost some health care personnel to the coronavirus, while others have taken the infection home to their families,” Sorkin said. “Vaccinating health care personnel at our member institutions saves lives.”

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