Covid-19 cases are rising sharply, especially in areas with low vaccination rates, leading CDC Director Rochelle Walensky on Friday to warn the country is experiencing "a pandemic of the unvaccinated."

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'A pandemic of the unvaccinated'

The United States is now averaging about 26,000 new Covid-19 cases every day, a 70% increase from the previous week, Walensky said—driven largely by the highly contagious delta variant. Meanwhile, hospitalizations have increased by 36%, and deaths have increased by 26%.

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Nearly all of the most serious cases are occurring in unvaccinated patients. According to CDC, more than 97% of people hospitalized with Covid-19 had not been vaccinated against the disease. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical advisor to the White House, recently said that 99% of recent Covid-19 deaths were among those who had not been vaccinated.

"This is becoming a pandemic of the unvaccinated," Walensky said. "We are seeing outbreaks of cases in parts of the country that have low vaccination coverage, because unvaccinated people are at risk."

States with low vaccination rates are experiencing especially significant surges. Florida, for example, is now reporting one-fifth of all new U.S. coronavirus cases.

The state's slow vaccination rollout, combined with its relatively low rates of mask-wearing, has made Florida "a ripe ground for the emergence of the delta variant," John Brownstein, CIO for Boston Children's Hospital, said. "The concern for the South is the summer months bring people indoors because of the heat," he added.

Jay Butler, deputy director for infectious diseases at CDC, said, "We're seeing positive effects of the vaccination problem, but at the same time … it ain't over 'til it's over. We're continuing to see transmission occurring, and we have a significant portion of the population that is unimmunized."

According to public health experts, even though Covid-19 cases are surging, the United States isn't likely to return to the peak case levels experienced over the winter and spring months. Rather, the country will experience more localized surges focused in areas with low vaccination rates.

"When you have populations of unvaccinated individuals, then the vaccines really can't do their jobs," Stacia Wyman, an expert in computational genomics at the University of California, Berkeley, said. "And that's where Delta is really a concern."

Officials say misinformation is a roadblock to vaccination

In response to rising Covid-19 rates, health officials reiterated their calls for Americans to get vaccinated.

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"Every person matters. Every shot matters. Every shot is progress," Jeff Zients, the White House Covid-19 response coordinator, said. "It's another life protected, another community that's safer. It's another step toward putting this pandemic behind us."

However, a recent CBS poll shows that unvaccinated Americans aren't as concerned about the delta variant as vaccinated Americans are.

According to the poll of 2,238 U.S. adults interviewed between July 14 and July 17, 48% of "not fully/not vaccinated" respondents said they were concerned about the delta variant, compared to 72% of fully vaccinated respondents.

The poll also found that, relative to an earlier poll taken in June, more unvaccinated people cited a distrust of science, concern about vaccine side effects, or distrust of the government as a reason for remaining unvaccinated.

Health officials have said they view misinformation as a significant obstacle to getting more Americans vaccinated, NPR reports.

Surgeon general Vivek Murthy on Friday said that health misinformation "has cost us lives."

"During this pandemic, health misinformation has led people to resist wearing masks and high-risk settings to turn down proven treatments, in some cases to turn to unproven treatments and to choose not to get vaccinated," Murthy said. "All of this has led to avoidable illnesses and deaths."

President Joe Biden echoed a similar sentiment when asked Friday about his message to social media companies.

"They're killing people," Biden said. "I mean, look, the only pandemic we have is among the unvaccinated. And they're killing people." (Baker, Axios, 7/19; Sullivan, The Hill, 7/16; Sullivan, NPR, 7/16; Anthes/Petri, New York Times, 7/16; Abutaleb/Sellers, Washington Post, 7/19; Joseph, STAT News, 7/19; Leatherby/Walker, New York Times, 7/17; Saric, Axios, 7/18; Mandavilli/Mueller, New York Times, 7/15; Montgomery, Axios, 7/19)