By Nikhila Natarajan New York, July 24 : America's Covid-19 curve is creeping up in the wrong direction, again. The "incredible efficiency" of the Delta variant is being blamed for Covid-19 cases roaring back in more than 90 per cent of US jurisdictions with severe outbreaks in parts of the country with low vaccination coverage. Unvaccinated people account for virtually all -- 97 per cent -- of Covid hospitalizations and deaths in the US, according to latest White House data. Three states -- Florida, Texas, and Missouri -- account for 40 per cent of all cases nationwide. The Delta variant is spreading with "incredible efficiency" and now accounts for more than 83 per cent of the virus circulating in the United States, Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), told reporters at a White House briefing. "If you are not vaccinated, please take the Delta variant seriously. This virus has no incentive to let up, and it remains in search of the next vulnerable person to infect," Walensky warned. She called the Delta variant "one of the most infectious respiratory viruses" she has seen in her 20-year career. All of the CDC data are currently pointing north. The current 7-day moving average of daily new cases (40,246) is up nearly 47 percent compared with the previous 7-day moving average. Hospitalisations continue to tick upwards and have been steadily increasing for the last one month. Of the four "variants of concern" in the US, the Delta variant is predicted to increase to the high 80 per cent level while all the other three - Alpha, Gamma and Beta are predicted to stay below the 9 per cent mark of total cases. A poll by a leading media outlet found that among unvaccinated people in the US, 45 per cent simply don't want to get vaccinated. The same poll showed that 64 per cent of unvaccinated Americans have little to no confidence the shots are effective against variants. As of July 22, 89 per cent of people ages 65 or older have received at least one dose of vaccine and 80 per cent are fully vaccinated. Nearly 69 per cent of people ages 18 or older have received at least one dose of vaccine and 60 per cent are fully vaccinated. For people ages 12 or older, 57 per cent are fully vaccinated. Shots for children under 12 years old are in the clinical trials stage and emergency use clearance is expected by Fall. "I didn't get the shots because I'm not sure what it'll do to me," said Natalie Petersen, in between bouts of coughing at a CVS waiting room in Union, New Jersey. "But now, I think I'll just get it done." The Covid-19 outbreak has killed more than 610,000 people in the US -- the country with the world's highest toll since the beginning of the pandemic in 2020. /IANS