Nationwide, the number of coronavirus cases has steadily plummeted for the past two months. But in a handful of states, things are trending in the wrong direction.

According to data compiled by The New York Times, five states are showing increases in COVID-19 cases over the past two weeks: Missouri (up 55%), Oklahoma (up 53%), Arkansas (up 46%), Utah (up 24%) and Arizona (up 8%).

All five of those states also have fully vaccinated less than 40% of their residents, and all rank in the bottom 16 in inoculation rates, according to data from the Centers for Disease Control and Prevention (CDC).

The percentage of the total U.S. population vaccinated is 45.2%, per the CDC, and 16 states and the District of Columbia have fully vaccinated a majority of their populations.

Four of the five problem states — Arizona being the exception — also are seeing increases in hospitalizations.

Missouri currently leads the nation in per-capita COVID-19 cases, and 13 of its counties account for the top 25 in the nation in new cases, according to The Times. Meanwhile, hospitalizations are up 12% over the past two weeks. 

Last week, the Missouri Department of Health said the state was experiencing a rise in cases of the Delta variant, which studies show is about 60% more transmissible and twice as likely to lead to hospitalization than the Alpha strain that was first detected in the United Kingdom. 

The CDC last week designated the Delta strain, first detected in India, a “variant of concern.” Health officials said Tuesday that the variant now accounts for 20.6% of the cases in the U.S., and CDC Director Dr. Rochelle Walensky expects it to eventually become the country’s dominant strain. 

The vaccines available in the U.S., however, appear to be highly effective against the variants.

“Our greatest concern in Missouri is areas with lower vaccine uptake,” Robert Knodell, the state’s acting health director, said last week. “With this variant being easier to spread and possibly causing more severe illnesses among unvaccinated people of all ages, vaccinations are the best way to stop this virus in its tracks.”

Adding to the concerns about the variant is that studies out of the United Kingdom have found that young people have been fueling its spread there, where it is now the dominant strain. The positivity rate for children ages 5 to 12 and young adults 18 to 24 was five times higher than for people 65 and older, according to an Imperial College London study.

For that reason, federal health officials are urging younger people to get vaccinated. 

“The reality is many younger Americans have felt like COVID-19 is not something that impacts them, and they've been less eager to get the shot,” White House COVID-19 response coordinator Jeff Zients told reporters Tuesday. “However, with the Delta variant now spreading across the country and infecting younger people worldwide, it's more important than ever that they get vaccinated.”

In Arkansas, Dr. Jennifer Dillaha with the state Department of Health said most of the people being hospitalized from COVID-19 are younger people. 

“Ninety-nine percent of the people who have been hospitalized since the vaccines have become available have been unvaccinated,” Dillaha told KATV-TV in Little Rock.

The Alpha variant remains the dominant strain in Arkansas, but Dillaha predicts the Delta strain will take over in a “few weeks.”

Dr. Anthony Fauci, President Joe Biden’s chief medical adviser, said Tuesday that if the Delta variant continues to spread and vaccination rates remain low in some states, “there is a danger … that you could see localized surges.”

Arkansas has the nation’s third-lowest inoculation rate, with just a third of its residents fully vaccinated. 

Arkansas Gov. Asa Hutchinson has been using social media to call attention to the increase in hospitalizations in recent days and urging residents to get vaccinated.

“Today’s report of increased hospitalizations is particularly concerning,” he tweeted Sunday. “We know the vaccine can dramatically reduce your risk of being hospitalized due to COVID-19, so take some time this week to go out and get the shot.”

Oklahoma has seen the second-highest increases in both coronavirus cases and hospitalizations of any state over the past two weeks. The Sooner State has a 37.3% rate for completed vaccinations.

Utah, meanwhile, has experienced the largest rise in hospitalizations, up 22%. It has fully inoculated just 35.9% of its residents.