Washington DC - The US continues to make rapid strides with its vaccination program, announcing on Sunday that health care workers carried out more than 4.6 million vaccinations the previous day.

"A new record," Cyrus Shahpar, the person responsible for vaccination data at the White House, said in a tweet announcing Saturday's figures.

White House coronavirus coordinator Jeff Zients had said on Friday that an average of three million vaccine doses were being administered every day in the US.

According to the US Centers for Disease Control, more than 183 million doses have been given out nationwide so far, and 45% of adults in the country have received at least one vaccine dose, while 27% of adults are fully vaccinated.

Three vaccines are currently being used in the US: in addition to the Moderna and BioNTech/Pfizer vaccines, for which two doses are needed, a vaccine from Johnson & Johnson is also being used, noted for taking full effect after just one dose.

President Joe Biden had promised before taking office in January that at least 100 million vaccine doses would be administered in his first 100 days in office.

The goal was reached after just 60 days in office. Biden then doubled his original target and is now aiming for a total of 200 million vaccinations by the end of April.

By the White House's count, more than 162 million vaccine doses have been administered since Biden took office – not including vaccinations in the weeks before his swearing in. Vaccine eligibility will be opened up to all adults on April 19.