The Centers for Disease Control and Prevention assigned two federal "surge team" members to Missouri this week to help fight the state's COVID-19 surge.
Missouri is among a growing list of states that have seen rising infections, with new cases increasing 46% over the last two weeks, from June 23 to July 7, with an average of 1,111 per week, up from 759 two weeks prior, according data from the Department of Health and Human Services. Over the past five weeks, infections have risen 180%.
Missouri and neighboring Arkansas now lead the nation with the highest weekly case rates per capita, which translates into more than 100 per 100,000 residents. New COVID-19 hospital admissions also rose 30% over the same two-week span, and front-line workers say patients are becoming sicker more quickly.
The CDC surge team assigned to Missouri is an epidemiologist, deployed to do on-the-ground genetic sequencing and data analysis, and an adviser who's working with local officials on how to address vaccine hesitancy.
Missouri's vaccination rate trails the national average. As of Friday, 46% of residents had received at least one dose, and 40% were fully vaccinated, according to the CDC, compared with 55% of all Americans who've gotten at least one shot and 48% who are fully vaccinated.
State health officials said they hope more help is on the way.
"We are looking forward to collaborating with them and learning more about how the Delta variant is impacting Missouri, specifically southwest Missouri initially," the Missouri health department said of the CDC, in a statement. "More team members will be added in the coming weeks, both remotely and in person, to assist with data and research, vaccine uptake strategies and outreach."
Low vaccination rates are having a profound impact on hospitals, particularly in the southwestern part of the state. At Mercy Hospital in Springfield, more patients are currently hospitalized than at any point during the pandemic. More than 88% of patients in the ICU are on ventilators, and the hospital had to request additional machines from other hospitals in its network when it ran out earlier this week.
"This is the absolute worst that I've ever seen it," Emily McMichael, a nurse at the hospital, told ABC News. "These patients are a lot sicker, and a lot younger, than what we saw the last go around, so it's just really sad to see. And a lot of the population is unvaccinated."
It's not just Mercy. At Lake Regional Hospital, in the Lake of the Ozarks area, the health system prepared for a surge this week.
"We are experiencing a spike in COVID-19 deaths in our community," Dane Henry, CEO of the Lake Regional Health System, wrote in a letter to the community Thursday. According to Henry, six COVID patients died in the hospital during the first week of July, compared with six deaths during all of June and only one COVID death in May.
"At Lake Regional, we are already stretched to the limit. Our hospital is very near capacity, and we are seeing exceptionally high numbers of Emergency Department patients daily," he wrote. "I'm also very worried about the decisions we will face if COVID cases surge, as expected. Hospitals all around us are filling up, too. That means none of us have a safety valve."
Top health officials have been warning for weeks that unvaccinated people have a high risk of contracting the delta variant of the virus, which was first identified in India and has since spread to more than 100 countries, including all 50 U.S. states. The variant is now dominant in the U.S. and is more transmissible than the original form of the virus, according to the CDC.
In Missouri, the delta variant makes up 73% of sequenced new cases, according to the CDC.
"We're seeing the real-world impact of what's happening across southwest Missouri and in our communities of the delta variant spreading rapidly through a largely unvaccinated population," Dr. William Sistrunk, an infectious disease specialist at Mercy, said a Wednesday press conference. "This variant is hitting and impacting our community very hard, and bringing down younger, healthier people."
Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University, pointed to the deep divide in hospitalization risk between vaccinated and unvaccinated Americans. "There are large swaths of the country where there are substantial numbers of communities that are under-vaccinated," he said. If the delta variant gets into one of those communities it "has the potential, because it is so very contagious, to spread and to cause infection."
While fully vaccinated people are fairly protected from severe disease and hospitalization from the delta variant, that's not true for the unvaccinated or partially vaccinated.
"It's very unusual for a fully vaccinated person to be admitted to the hospital," Schaffner said. "Virtually every one of those hospitalizations could have been prevented."
ABC News' Anne Flaherty contributed to this report.