HOUSTON - With the increase of confirmed COVID-19 cases in the southern US state of Louisiana, health experts believed the more contagious Delta variant is established in the state with higher vulnerability among the unvaccinated, local media reported on Thursday.

State figures showed that over the last week, cases have increased by 3,360 in Louisiana, the biggest spike since March 4. Cases have more than doubled over the last 14 days. Health experts said this was likely an effect of the Delta variant making its way into unvaccinated hosts.

"Across the country, the spike will be bigger in the areas that have lower vaccination rates, which unfortunately is us and a number of our neighboring states," local media NOLA.com quoted Joe Kanter, assistant secretary of health, as saying.

With one of the lowest vaccination rates in the country, Louisiana residents have a higher risk for coronavirus infection. Just 39 percent of the population has received at least one dose of vaccine.