A 12-year-old girl will receive the Pfizer BioNtech vaccine in New York City on May 14, 2021.

Adam Jeffery | CNBC

More than half a million 12 to 15 year olds have received a Covid-19 vaccine to date – less than a week since the Centers for Disease Control and Prevention opened it for public distribution, said Director Dr. Rochelle Walensky on Tuesday.

On Wednesday, the Advisory Committee on Immunization Practices endorsed the use of the Pfizer Covid-19 vaccine for adolescents ages 12-15. Pfizer previously said studies had shown its vaccine to be 100% effective in children ages 12-15.

“Last week the FDA approved the use of the Pfizer vaccine for adolescents and recommended the CDC. In less than a week, we have more than 600,000 12-15 year olds and a total of more than 4.1 million teenagers ages 12 to 17 years old have been vaccinated so far. My own son was one of them, “said Walensky.

President Joe Biden’s goal is to vaccinate 70 percent of American adults by July 4th. Vaccinating adolescents vaccinates 70 to 85% of the total population, which experts say is necessary to achieve herd immunity. About 80% of seniors have received at least one dose. Children make up 20% of the US population.

“Yesterday was an important day and the president announced that more than 60% of people aged 18 and over had received at least one dose of vaccine,” said Walensky. “We must continue to ensure that vaccination rates are consistent across the country.”

Hospital admissions and Covid-19-related deaths are declining in the US, and the country is administering about 1.5 million shots a day, according to the CDC. There has been a downward trend in vaccinations in the United States since April.

The US also has its lowest daily case numbers since June 2020. The 7-day average for deaths fell 8% from last week to around 600 deaths per day, according to John Hopkins University.

“We have made really tremendous strides across the country to make sure people have access to vaccines and we have a lot more to do. We are administered more than 274 million times,” Walensky said. “If you haven’t been vaccinated, you may consider being our reason to celebrate another.”

Correction: This article has been updated to correct Biden’s July 4th goal. He wants 70% of all adult Americans to be vaccinated by that day.