Travelers look at Covid-19 results after being tested inside JFK International airport in New York on December 22, 2020.Kena Betancur | AFP | Getty ImagesFederal health officials are continuing to push for more Americans to get vaccinated as the delta variant accounts for a bigger share of new cases in the United States.”You have to get vaccinated in order to be protected from Covid-19, the delta variant and any other variant that might come down the road,” Jeffrey Zients, White House coronavirus response coordinator, told reporters during a briefing Thursday.The variant, first detected by scientists in India, has now spread to more than 80 countries and accounts for more than 10% of new cases in the U.S., up from 6% last week.”If you are vaccinated, you are protected, and if you are not, the threat of variants is real and growing,” U.S. Surgeon General Dr. Vivek Murthy said in the briefing Thursday after explaining that the delta variant is “significantly more transmissible and may be more dangerous than prior variants.”The Centers for Disease Control and Prevention recently designated the delta variant as a variant of concern “based on mounting evidence that the delta variant spreads more easily and causes more severe cases when compared to other variants, including B.1.1.7 (Alpha),” it said in a statement to NBC News.New cases and deaths are down dramatically in the U.S., thanks to generally successful vaccination campaigns in many states. Some pockets of the country are still seeing a rise in cases and hospitalizations.”We’re seeing that communities with the highest vaccination rates have lower rates of new cases and hospitalizations, and communities with the lowest vaccination rates have higher new cases and hospitalizations,” Zients said.The United Kingdom recently saw the delta variant become the dominant strain there, surpassing its native alpha variant, which was first detected in the country last fall. The delta variant now makes up more than 60% of new cases in the U.K.Dr. Anthony Fauci, chief medical advisor to the president, said last week that “we cannot let that happen in the United States,” as he pushed to get more people vaccinated, especially young adults.