A healthcare worker holds syringes with the Moderna and Pfizer vaccines against the coronavirus disease (COVID-19) at a vaccination centre, in El Paso, Texas, May 6, 2021.Jose Luis Gonzalez | ReutersThe seven-day average of new U.S. Covid cases fell further on Tuesday to about 24,155 infections per day, according to data compiled by Johns Hopkins University, and the average pace of daily deaths is also on the decline.The latest data from the Centers for Disease Control and Prevention shows that half of adult Americans are now fully vaccinated against Covid.For those not vaccinated, CDC Director Dr. Rochelle Walensky urged caution over the upcoming Memorial Day holiday, noting that those who have gotten a shot are protected.”If you are not vaccinated, our guidance has not changed for you,” Walensky said at a White House press briefing Tuesday. “You remain at risk of infection, you still need to mask and take other precautions.”Last year, U.S. Covid cases rose following the holiday weekend, when there were no vaccines available at the time.U.S. Covid casesThe U.S. is reporting an average of about 24,155 infections per day over the past week, down 23% from a week ago and a steep decline from the most recent high point of more than 71,000 cases per day in mid-April.A CNBC analysis of Hopkins data shows that average case counts have declined by at least 5% in 41 states and the District of Columbia over the past week.U.S. Covid deathsThe U.S. is seeing an average of 520 Covid deaths per day over the last week, according to Hopkins data.The total number of reported Covid deaths in the U.S. since the start of the pandemic is now about 591,000.U.S. share of the population vaccinatedAbout 50% of the U.S. population has had at least one shot, according to the CDC, with more than 131 million Americans, or almost 40%, fully vaccinated.Of those aged 18 and older, about 62% have received at least one dose of a vaccine, while 50% have now been fully vaccinated. President Joe Biden’s goal is to get the share of adults with one dose or more to 70% by July 4.U.S. vaccine shots administeredThe seven-day average of vaccinations administered in the U.S. is 1.8 million per day over the past week, according to CDC data. That figure has hovered between 1.7 and 2 million for more than a week.