The United States is seeing its fewest number of deaths from Covid-19 since the start of the pandemic, official data showed Tuesday.

The seven-day moving average of deaths was 545 on May 16, and "the last time our seven-day-average was this low was in March 2020, essentially since the pandemic began," Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC) said at a briefing.

New daily cases are headed down in all US states, with the current average of 30,211 the lowest since last June -- when there were severe testing shortages.

"We are winning the war on the virus, and we need you to help us finish the job," White House senior advisor for Covid response Andy Slavitt said, calling on remaining eligible Americans to get vaccinated. 

About 60 percent of the US adult population has now received at least one dose of a Covid vaccine, and the country is moving to loosen restrictions. 

Last the week the CDC amended its guidance to say that vaccinated people do not need to wear masks either outdoors or indoors for most activities, a move welcomed by many experts, though some said it might have been premature. 

The US has also authorized the Pfizer vaccine for children aged 12 and up and more than 600,000 12-to-15-year-olds have now received their first shots, added Walensky.