Updated

Half of all American adults will be fully vaccinated against COVID-19 as of Tuesday, White House senior COVID advisor Andy Slavitt announced during a White House COVID-19 briefing. 

"Today, the U.S. will hit 50% of adult Americans that are fully vaccinated," Slavitt said. "This is a major milestone in our country’s vaccination efforts."

Across the country, 25 states and the District of Columbia have fully vaccinated 50% or more of their adult population, Slavitt said, and nine states recently reached 70% of adults with at least one shot. Federal data indicates over 128 million U.S. adults have completed a vaccination series, with 74% of adults over the age of 65 now fully vaccinated. 

CDC REPORTS 10K BREAKTHROUGH COVID-19 CASES AMID 101M VACCINATED PEOPLE

Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC) said COVID-19 infections, hospitalizations and deaths continue to decline as more Americans become vaccinated. She specifically noted a seven-day average of 22,877 cases per day, marking an approximate 25% decrease over the prior seven-days. The figures also reflect one week with a seven-day average below 30,000 cases. The seven-day average for COVID-19 related hospital admissions is 3,080, down nearly 17% from the prior period, with daily deaths at 501.

As Memorial Day weekend approaches, Walensky said unvaccinated populations remain at risk of infection, and should follow federal health guidance like wearing masks.

 "We are on a good downward path but we are not quite out of the woods yet," Walensky said. "Cases, hospitalizations and deaths are all declining because of the millions of people who have stepped forward and done their part to protect their health and the health of their communities to move us out of this pandemic."

The news comes as Moderna announced Tuesday its COVID-19 vaccine demonstrated 100% efficacy in adolescents aged 12 to 17 in a late-stage clinical trial. The company plans to submit the data to regulators around the world in early June. Pfizer’s COVID-19 vaccine cleared regulatory hurdles for use in kids aged 12-15 in mid-May, bolstering hopes kids can receive vaccines before the 2021-2022 school year.

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President Joe Biden is aiming for 160 million U.S. adults to be fully vaccinated against coronavirus by July 4. Biden is also aiming for 70% of the U.S. adult population to have one vaccine shot by July 4.