New daily cases are declining in all states, with a current national average of 30K the lowest since last June, when testing was very low.

The United States also recorded the lowest number of coronavirus-related deaths since the start of the pandemic and, according to the US government's chief health advisor the country is "winning the battle" against the virus.

The seven-day average number of deaths was 545 on May 16, and "the last time it had been this low was in March 2020, essentially when the pandemic began," Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), told reporters this week.

"We are winning the war against the virus and we need you to help us finish the job," said White House Senior Advisor for the Pandemic, Andy Slavitt, who called on Americans to comply with care requirements and for those who have not yet been vaccinated to do so.

About 60% of the adult population has so far received at least one dose of a jab, prompting authorities to ease restrictions.

In any case, the United States remains the worst-hit country by COVID, with 33 million infections and 586,000 deaths, according to the latest official figures.