US President Joe Biden says he wants 70 percent of American adults to have at least one coronavirus vaccine shot by July 4.

Biden unveiled the target on Tuesday, along with the aim of getting 160 million US adults fully vaccinated by the same date, the nation's Independence Day holiday.

The president also announced efforts to increase the number of venues for walk-in vaccinations, as well as boosting pop-up clinics and mobile units in rural areas.

Biden is trying to convince more Americans to get vaccinated, referring to it as "a choice of life and death."

He said receiving shots would help people and their loved ones stay safe, get businesses open again and get the country back to normal.

The Centers for Disease Control and Prevention says that as of Monday, 56.3 percent of those aged 18 or above in the US had received at least one shot of coronavirus vaccine.

But the daily number of people getting vaccinated began to decrease around mid-April.