The daily average of new coronavirus cases has nearly tripled over the past two weeks, as the delta variant races across the U.S. and ravages states with low vaccination rates, particularly in the South.

Every state has seen its daily case count increase during that period. Among them, 21 saw their numbers double, 19 reported cases tripling and two even saw their numbers quadrupled, according to data from The New York Times.

On top of that, public health officials say that unvaccinated individuals account for almost all of the COVID-19 hospitalizations and deaths that are now on the rise. Anthony Fauci, President Biden’s chief medical adviser, declared Sunday that the “outbreak among the unvaccinated” has begun.

Here’s what you need to know about the latest pandemic surge.

Majority of Americans still aren’t fully vaccinated

With less than half of the U.S. population fully vaccinated, a majority of Americans remain at risk of contracting the coronavirus and becoming seriously ill.

The 10 states with the highest number of daily cases per capita all have less than 50 percent of their residents fully vaccinated, according to data from the Times and Mayo Clinic. Those states are Arkansas, Louisiana, Florida, Missouri, Mississippi, Alabama, Nevada, Alaska, Oklahoma and Kansas.

Eight of the 10 have reported less than 55 percent of their adult population is fully vaccinated, below the national average of 60 percent.

Overall, 49.1 percent of Americans, including those ineligible to get the vaccine, are considered fully vaccinated, according to the Centers for Disease Control and Prevention.

Health experts say the states with rates below that mark are more susceptible to new outbreaks like the one spreading across the U.S.

“It’s really an outbreak among the unvaccinated,” Fauci told CNN’s “State of the Union” on Sunday. “So this is an issue, predominantly among the unvaccinated, which is the reason why we're out there practically pleading with the unvaccinated people to go out and get vaccinated.”

Federal health officials have said that about 97 percent of COVID-19 hospitalizations occur among unvaccinated people — a statistic that White House press secretary Jen Psaki reiterated to reporters on Monday.

“The more people vaccinated, the more the county will be safe,” she said, while acknowledging the rare occurrences of breakthrough cases among fully vaccinated people.

Administration officials are hopeful that recent concerns about the delta variant are starting to hit home with millions of Americans who were previously unvaccinated.

Psaki on Monday said almost 500,000 people got their first shot on Sunday.

“Numbers like this signal to us people are understanding the urgency and importance of getting vaccinated and rightfully so,” Psaki said during a White House briefing.

But not all Americans can get vaccinated. The Food and Drug Administration has not authorized a COVID-19 vaccine for children under the age of 12, leaving millions of kids at a higher risk of contracting the virus.

Surge is hitting the South and GOP-led states

States in the South, as well as others led by Republican governors and legislatures, are some of the hardest hit in the latest coronavirus spike.

States that voted for former President Trump in the 2020 election are more likely to be among those with the highest case counts per capita when compared with states won by President Biden.

Twelve of the top 15 states with the highest cases per 100,000 people voted for Trump, and 11 of the 15 states with the lowest cases per capita went for Biden.

The three states that White House coronavirus response coordinator Jeff Zients said made up 40 percent of all cases nationwide — Florida, Texas and Missouri — all supported the former president in November.

In addition, 14 of the 15 states with the lowest rate of fully vaccinated residents sided with Trump last year, while the 15 states with the highest rates of full vaccination all awarded their electoral votes to Biden.

The South has seen a major spike in cases throughout July, reaching 25 per 100,000 people on Sunday, according to the Times, more than four times the rate in the Northeast.

The partisan divide in vaccination rates has been documented by the Kaiser Family Foundation, which earlier this month found counties that voted for Trump are lagging in vaccinations. The study found 47 percent of residents in Biden counties and 35 percent of those in Trump counties were fully vaccinated.

As red state cases increase, Republican lawmakers are becoming more outspoken about the importance of vaccines. House Minority Whip Steve Scalise (R-La.) said he got his first COVID-19 shot last week due to concerns over the delta variant.

On Sunday, Fauci called on leaders in struggling areas to promote the vaccine, noting he’s been “heartened” to hear people like Scalise talk about the benefits of vaccination.

“What I would really like to see is more and more of the leaders in those areas that are not vaccinating to get out and speak out and encourage people to get vaccinated,” he told CNN. 

Not all states with high COVID-19 case counts voted for Trump: Nevada awarded its electoral college votes to Biden, yet ranks seventh in COVID-19 cases per capita, according to the Times.

Cases in Arkansas are skyrocketing

Arkansas on Monday had the highest rate of infection in the country, with 60 cases per 100,000 residents. The following day, Louisiana claimed the top spot.

Eric Topol, a professor of molecular medicine at Scripps Research, tweeted on Monday that Arkansas represents the “US outlier leading the Delta wave for new cases.”

Since June 27, the state’s seven-day average case count has catapulted from 236 to its current rate of 1,548 cases per day. In the past two weeks, COVID-19 cases have nearly doubled, hospitalizations have risen by 63 percent and fatalities have doubled.

One hospital, the University of Arkansas for Medical Sciences, marked its highest number of COVID-19 patients throughout the pandemic on Monday, Chancellor Cam Patterson tweeted over the weekend.

The state also has the third lowest full vaccination rate, at 36 percent of the total population, while 45.5 percent of all residents have gotten at least one shot, according to the Mayo Clinic.

Arkansas Gov. Asa Hutchinson (R) bemoaned that vaccines had become “political” in an interview last week, later telling CNN on Sunday that opposition to the vaccine has “hardened” in his state due to “false information.”

"It is myths,” he said on “State of the Union.”

“As I go into these town hall meetings, someone said: ‘Don't call it a vaccine; call it a bioweapon.’ And they talk about mind control. Well, those are obviously erroneous. Other members of the community correct that."

Sarah Huckabee Sanders, who served as White House press secretary under Trump and is now running for governor of Arkansas, advocated for the vaccine in a Sunday op-ed in the Arkansas Democrat-Gazette, framing it as the "Trump vaccine."

“I believe the Trump vaccine will help keep our state open for business and our economy growing,” she wrote. “It's clear that the Trump vaccine works and is saving lives.”