RELATED: The CDC Says Vaccinated People Who Get COVID Have This in Common. During a White House press briefing on June 22, COVID adviser Anthony Fauci, MD, revealed that the U.S. is following a similar “pattern with the Delta variant” that the U.K. has. Recent data from Public Health England revealed that 99 percent of cases in the country are the result of the Delta variant, which originated in India.ae0fcc31ae342fd3a1346ebb1f342fcb Fauci says the U.S. is headed in the same direction. According to the infectious disease expert, 20.6 percent of people with COVID in the U.S. right now are infected with the Delta variant. This is more than double the percentage that was seen two weeks ago on June 5, when the variant made up only 9.9 percent of cases. And two weeks before that, on May 22, just 2.7 percent of cases in the U.S. were caused by the Delta variant, per Fauci. “Similar to the situation in the U.K., the Delta variant is currently the greatest threat in the U.S. to our attempt to eliminate COVID-19,” Fauci said. According to Fauci, the transmissibility of the Delta variant is “unquestionably greater” than the original strain of COVID and the current dominant U.S. variant, Alpha. “It is associated with an increased disease severity, as reflected by hospitalization risk, compared to Alpha,” Fauci said. RELATED: For more up-to-date information on COVID delivered straight to your inbox, sign up for our daily newsletter. There is good news, however. “Our vaccines are effective against the Delta variant,” Fauci said. According to the infectious disease expert, the Pfizer vaccine is still 88 percent effective against Delta in terms of symptomatic disease and 92 percent effective against hospitalizations two weeks after the second dose. “We have the tools, so let’s use them and crush the outbreak,” Fauci said, urging those in the U.S. to get vaccinated. According to the CDC, only 45.3 percent of U.S. adults are fully vaccinated. “We know our vaccines work against [the Delta] variant. However, this variant represents a set of mutations that could lead to future mutations that evade our vaccine.  And that’s why it’s more important than ever to get vaccinated now, to stop the chain of infection, the chain of mutations that could lead to a more dangerous variant,” CDC director Rochelle Walensky, MD, said during the same briefing. RELATED: 99 Percent of People Hospitalized for COVID in 2021 Have This in Common.