Covid cases are on the rise in all 50 states and the District of Columbia as the Delta variant spreads rapidly in the US and the virus once again tightens its grip.

The U.S. reports an average of about 43,700 new cases per day over the past week – well below pandemic highs but up 65% in the past seven days and nearly three times what it was two weeks ago, data compiled by Johns Hopkins University were indicates. Cases hit a 15-month low in late June before starting to rise again as fewer people were vaccinated and the more contagious Delta variant caught on in the country.

Vaccination rates peaked in April, at more than 3 million vaccinations per day, but have declined significantly in recent months to around 530,000 per day, according to data from the Centers for Disease Control and Prevention.

Louisiana, Arkansas, Missouri, Florida and Nevada reported the highest daily average of new cases per capita for the past week, all of which are at least twice the US rate.

Each of these states also have vaccination rates below statewide levels, with the largest gap visible in Louisiana, where 47.7% of the eligible population ages 12 and older received vaccination or more, compared with 65.9% across the country.

According to the Centers for Disease Control and Prevention, hospital admissions for Covid patients have increased by 32% compared to a week ago. The number of daily Covid deaths, which typically lag a few weeks or more behind a surge in case numbers, has increased, but not at the same pace as cases or hospitalizations. Many Americans who are most susceptible to the virus now also have some level of protection, with 89% of seniors having at least one vaccination.

“The death toll has not increased because we have done an incredible job to fully vaccinate the populations most likely to die from Covid-19, especially those over 65 and nursing home residents,” said Dr. Peter Chin-Hong, an infectious disease specialist at the University of California at San Francisco, said in an interview. “The deaths are also lagging behind the infection rate in some cases, but I also assume that the death rate will not change.”

The overwhelming majority of severe Covid cases – 97% of hospital admissions and 99.5% of Covid deaths – occur in those who are not vaccinated, U.S. surgeon general Vivek Murthy told reporters at a White House briefing Thursday .

President Joe Biden and CDC Director Dr. Rochelle Walensky have both described the current state of the outbreak as “a pandemic of the unvaccinated”.

US officials are urging Americans to get vaccinated against the Delta variant, which Walensky says is one of the most contagious respiratory diseases scientists have ever seen. With 68.6% of the adult population at least partially vaccinated, the US still hasn’t met Biden’s July fourth goal of 70% of Americans 18 years of age and older to receive one or more vaccinations.

The variant is highly contagious, mainly because people infected with the Delta strain can carry up to 1,000 times more virus in their nasal passages than those infected with the original strain, according to new data.

“The Delta variant is more aggressive and much more transmissible than previously circulating strains,” Walensky told reporters at a briefing Thursday. “It’s one of the most contagious respiratory viruses we know and that I’ve seen in my 20-year career.”

Local officials across the country are now asking Americans to return to wearing masks indoors. Several California and Nevada counties are now advising all residents to wear masks in public indoor spaces, regardless of whether they are vaccinated or not. Local leaders in at least three other states have reintroduced mask mandates, issued face-covering recommendations, or threatened the return of strict public health limits for all residents – despite CDC guidelines that vaccinated individuals do not use these protocols in most settings must follow.

“The easiest and best and most effective way to prevent a new variant from emerging and destroy the existing Delta variant is to get everyone vaccinated,” said Dr. White House Chief Medical Officer Anthony Fauci in an interview with CNBC on Wednesday.

– CNBC’s Bob Towey contributed to the coverage.