New COVID-19 cases plummet to lowest levels since last June

A server, right, glances at a patron's phone while seating patrons and taking orders at Tiki Bar on Manhattan's Upper West Side on Monday, May 17, 2021, in New York. Vaccinated New Yorkers could shed their masks in most situations Wednesday, and restaurants, shops, gyms and many other businesses can go back to full occupancy if all patrons are inoculated. Subways resumed running round-the-clock this week and midnight curfews for bars and restaurants will be gone by month's end. (AP Photo/Kathy Willens)

A person holds a mask while walking outside in Philadelphia on Friday, May 21, 2021. (AP Photo/Matt Rourke)

New coronavirus cases across the United States have tumbled to rates not seen in more than 11 months, sparking optimism that vaccination campaigns are stemming both severe COVID-19 cases and the spread of the virus.