As the highly transmissible Delta variant spreads nationwide, the Centers for Disease Control and Prevention (CDC) and the State Department are urging Americans to avoid traveling to the UK.

But that’s not going far enough, U.S., Dr. Ebony Jade Hilton, GoodStock Consulting co-founder and medical director, told Yahoo Finance Live. In fact, Americans should be careful traveling to certain areas within the U.S.

“If we’re going to talk about traveling to the U.K., then we should also caution Americans about traveling to Florida,” Hilton said. “Right now, one in every five new COVID cases are coming out of Florida.”

In Florida, only 47% of the population is fully vaccinated as the state is seeing an average of 55.1 daily new COVID-19 cases per 100,000 people, the highest rate in the country, according to data from the Brown School of Public Health. And according to the Florida Department of Health's weekly COVID-19 report, the number of new COVID-19 cases nearly doubled in the state last week from the prior week.

'The Delta variant is a game changer'

During a press briefing on Friday, White House Coronavirus Response Coordinator Jeffrey Zients said four states accounted for more than 40% of all cases in the past week, with 20% of new cases occurring in Florida alone.

Arkansas is also among the nation’s current pandemic hot spots. Brown School of Public Health data shows the state is reporting an average of 38.1 daily new COVID-19 cases per 100,000 people, and is designated “red” on the risk-assessment map.

“We're seeing an uptick across the Southeast, and even to the Midwest,” Hilton said. "We're looking at places like Alabama and Arkansas. So we can talk about the rest of the world, but the United States really needs to hone in and focus on what is preventing us from having a successful vaccine rollout in those heavily hit areas.”

Vaccinations are the key to slowing the spread of the Delta variant. In Alabama, where only about 33% of the population is fully vaccinated, the state department reported a 39% jump in COVID-19 cases from June 26 to July 9, and unvaccinated people represented 96% of COVID-19 deaths in the state since April 1.

Nationwide, Johns Hopkins University data shows a total of 243,110 new cases were reported last week as the Delta variant spreads, accounting for about 40% of the total cases in the past month.

“The Delta variant is a game changer,” Hilton said. “New cases nationwide are up 140% in the last two weeks. Our hospitalizations are up 34%, and our deaths, unfortunately, are increasing by 33%. We're not finished with this pandemic.”