RELATED: Dr. Fauci Just Said He’s Worried About This State. Epidemiologist Michael Osterholm, PhD, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told CNN that the next few months are hard to predict, but when it comes to the short term, he has a hypothesis. “[If] the Delta variant follows this pattern that it’s taken in other countries, we can expect to see, particularly the Southern Sun Belt states that are getting hit so hard right now … a really rapid decline in cases probably in two to three weeks,” said Osterholm.ae0fcc31ae342fd3a1346ebb1f342fcb The states traditionally considered to be part of the Sun Belt include Alabama, Arizona, Florida, Georgia, Louisiana, Mississippi, New Mexico, South Carolina, Texas, roughly two-thirds of California, and some parts of North Carolina, Nevada, and Utah. According to data from NPR, all of these states are currently in the red zone, meaning they’re at the highest COVID risk level and are seeing more than 25 daily new cases per 100,000 people. Louisiana, Mississippi, and Florida are all seeing more than 100 new cases per capita each day. RELATED: For more up-to-date information, sign up for our daily newsletter. Osterholm’s prediction is likely partly based on the trajectory of the Delta surge in the U.K., which began to fall off in late July. The Boston Globe reports that COVID cases in the Netherlands and India also experienced similar declines following a Delta variant-induced spike. While experts aren’t positive what the drop-offs can be attributed to, many cite herd immunity, which is when enough people in a population are protected from a virus, either due to natural infection or vaccination, and as a result, it can no longer spread so quickly. “If you have a combination of natural immunity induced by infection with Delta, and then you have fairly high levels of vaccine coverage, you’re going to get to a level of herd immunity that will drive down transmission and potentially lead it to stop or at least slow down to much lower levels,” David Hamer, MD, an infectious disease specialist at Boston Medical Center, told The Boston Globe. Hammer said he’s currently “cautiously optimistic” about the trends he’s seeing abroad. RELATED: If You Got Pfizer, This Is When You’re More Likely to Get Breakthrough COVID. But while some states may see a decline in cases as soon as two to three weeks, others will remain in the thick of it for longer. Osterholm said parts of the country that are just now seeing COVID cases spike—like those in the Midwest and some areas of the Northeast—may soon succumb to a similar fate as the Sun Belt states, which could prolong the surge. “The real challenge is what’s going to happen with all the other states where we’re seeing increases,” Osterholm told CNN. “If they too light up, then this surge could actually go on well into mid-September or later.” The Washington Post hypothesizes that contact tracing, summer break from school, and widespread vaccination may be part of the reason that the U.K.’s cases have dropped. Now, experts in the U.S. are urging people to use the same tools to suppress the Delta surge. “Things are tough right now with Delta because we’ve heard how transmissible it is and how people who are vaccinated can carry high loads of virus in their noses,” Linsey Marr, PhD, an expert in the transmission of infectious diseases via aerosols, told CNN. “But I think we can be reassured that the vaccines still provide excellent protection against hospitalization, serious cases of illness.” Marr emphasized that with a more transmissible variant, we need to be even more vigilant. “We know what works and, [even] with a more transmissible virus, those things still work: the masks, the distancing, ventilation, filtration, and avoiding crowds,” she said. RELATED: Virus Experts Have Stopped Going to These 4 Places as Delta Surges.