President Biden on Friday said the United States will not enter another "lockdown," despite the "serious and deadly threat" of the Delta variant of COVID-19, but he urged unvaccinated individuals to get their shots. 

Biden, who spoke at the White House, was asked whether the severity of the new strain of COVID-19 could send the U.S. back into a lockdown, to which he replied: "I don't think so." 

"So many people have already been vaccinated, but the Delta variant can cause more people to die in areas where people have not been vaccinated," he said. 

"Existing vaccines are very effective," Biden continued. "So no, it is not a lockdown, but some areas could be very hurt." 

The president announced that 65% of American adults have received at least one COVID-19 shot, saying the administration turned the pandemic around by acting "quickly, aggressively and equitably." He touted the 300 million COVID-19 vaccines administered to Americans in less than 150 days. 

CDC LABELS DELTA COVID STRAIN A ‘VARIANT OF CONCERN’ 

"Thanks to this wartime response, we've gotten 300 million shots in the arms of Americans in 150 days--months ahead of what anyone thought was possible when we started," Biden said, noting that "people were skeptical" over whether they would be able to reach 100 million shots in his first 100 days in office. 

"We did it, and we kept going," he said. 

The president, though, said that while the U.S. is making "incredible progress," the threat of COVID-19 is still "serious and deadly," referring to the Delta variant of COVID-19, which the Centers for Disease Control and Prevention designated this week as a "variant of concern." 

"If you are unvaccinated, you are at risk of being seriously ill or dying or spreading it," Biden said. "People getting seriously ill, being hospitalized due to COVID-19 are those who have not been fully vaccinated." 

The president said, "The new variant will leave unvaccinated people even more vulnerable than they were a month ago." 

Biden explained that experts said the Delta variant is "more easily transmissable" and "deadlier and particularly dangerous for young people." 

"But the good news is, we have the solution," he said. "The science and the data are clear--the best way to protect yourself against these variants are to get fully vaccinated." 

The president went on to urge half-vaccinated Americans to get their second shot "as soon as you can."  

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The CDC this week labeled the Delta variant one of "concern"--a change officials told Fox News was based on "mounting evidence" that the variant spreads more easily and causes more severe cases when compared to other variants.

Biden administration officials told Fox News that they are studying the effectiveness of Johnson & Johnson's one-dose vaccine and "remain optimistic," as overseas, the AstraZeneca vaccine has demonstrated effectiveness against Delta. An official told Fox News the AstraZeneca vaccine is "built on a similar platform as Johnson & Johnson." 

The official told Fox News that vaccinated people have a "high degree of protection" but warned that those who are not vaccinated "are at risk."

The CDC’s classifications define three classes of variants of COVID-19 – variants of interest, variants of concern, and variants of high consequence. 

According to the CDC, a variant’s classification status can change as officials learn more about them. 

"CDC and SARS-CoV-2 Interagency Group continually review the available scientific evidence and the genomic surveillance data to assess the classification of variants," the CDC said. 

According to the CDC, "variants of concern" may require several public health actions, like notifying the World Health Organization under International Health Regulations, reporting to CDC, local or regional efforts to control the spread, increased testing, or research to determine the effectiveness of vaccines and treatments against the variant. 

"Based on the characteristics of the variant, additional considerations may include the development of new diagnostics or the modification of vaccines or treatments," the CDC said, adding that "investigations are underway to further characterize this variant of concern and its potential effect on current vaccines and treatments.