The pandemic has taken the lives of 663,913 people in the U.S. That is 1 in 500 Americans who have perished from COVID-19, according to the latest statistics from the United States Census Bureau. The agency’s April figures show a total U.S. population of 331.4 million.

According to CNN, this sobering reality comes as the country is still grappling with a surge of COVID-19 hospitalizations, including children. Officials are calling for vaccine mandates in the workplace and masking in schools in the hopes of preventing further deaths from the insidious disease.

Data from the Centers for Disease Control and Prevention reveals that we had a 30% increase in the number of daily cases in the U.S. and nearly three times the number of deaths in the past month.

And it comes with a high price tag. The cost of unvaccinated patients who needed hospital care spiked in August. According to a Kaiser Family Foundation report, the price of hospital stays for this population soared to $3.7 billion in August and $5.7 billion since June. These preventable costs did not include the number of breakthrough cases for vaccinated patients, according to Forbes.

Only 54% of the U.S. population has been fully vaccinated, and experts say that vaccines are the best source of protection against COVID-19. The vast majority of deaths from the disease have occurred in the unvaccinated. In Pennsylvania, between January 1 of this year and September 7, 97% of the state’s COVID-19 deaths were among unvaccinated people, says CNN.

With the Delta variant surging across the country, recent data released by the federal government shows that in hospitals throughout the South as well as in California and Oregon, more than 50% of patients are being treated for COVID-19. Anything above 20% represents “extreme stress” for hospitals, says NPR, according to a framework developed by the Institute for Health Metrics and Evaluation at the University of Washington. The most critical patients are all unvaccinated, says Kaiser Health News,

The CDC recommends wearing masks indoors and in crowded venues even if you are vaccinated. The Delta variant has a deadly viral load that can be transmitted even among vaccinated people. Dr. Anthony Fauci told CNN Tuesday that vaccinations and masks are the ways to keep children safe in school.

“If you surround the kids with vaccinated people and you have everybody wearing a mask, you get a situation where the children will be relatively safe in school,” Fauci said.

Disputes over vaccine mandates have been brewing across the country, with religious organizations fighting for exemptions. In New York, Catholic and Baptist medical professionals filed a complaint against the state’s vaccine mandate for healthcare workers. A federal judge on Tuesday issued a temporary order suspending New York state from enforcing the mandate.

Companies and institutions can file for medical exemptions, but experts say these are few and far between.

For the unvaccinated who have been felled by COVID-19, experts say they are deeply remorseful for not heeding the advice of experts.

Lydia Mobley, an intensive care unit nurse working at a hospital in central Michigan, says she sees many patients on every shift who regret not taking the warnings seriously.

“A lot of times before they’re intubated — which means put on a ventilator because they can’t breathe on their own — when they’re still struggling to breathe, and they’re saying, ‘Well, I didn’t know COVID was real, and I wish I’d worn a mask.’ And then it’s already too late,” she told NPR’s All Things Considered. “You can see the regret as they’re struggling to breathe and it’s finally hitting them that this is real. It makes me very sad.”