New York City and Los Angeles, the two largest public school districts in the United States, have announced plans to fully reopen schools, as part of a parent-led nationwide trend amid a sustained decline in COVID-19 infections and rise in vaccinations.
"It's time for everyone to come back, it's time for us all to be together, time to do things the way they were meant to be done," New York City Mayor Bill de Blasio told reporters on Monday.
The city's 1.1 million public school students have adopted different learning practices so far this year. Some have split their time between school and home, while others are still being taught full time by "remote learning". Neither of those options would be offered as of September, de Blasio said.
In Los Angeles County, all students in elementary, middle and high schools - more than 600,000 pupils - would be allowed to attend class full time, said district superintendent Austin Beutner. However, students and some teachers would have the option to remain at home, he said.
United Teachers Los Angeles, the union representing most teachers in the district, has resisted fully reopening schools until additional health and safety measures are in place.
New York and Los Angeles join New Jersey and several other states reopening schools as officials make progress tackling the spread of the coronavirus.
Nationwide, the number of new infections fell to a seven-day average of 22,877 on Sunday, the lowest since June, according to the Centers for Disease Control and Prevention.
Nearly half the US population has had at least one dose of a vaccine, according to the CDC. In New York, 52 per cent of residents has had at least one shot, Governor Andrew Cuomo says.
The pace of vaccinations has been trailing off to a seven-day average of about 1.7 million doses a day, according to the CDC data, from its April peak of about 3.3 million.
The decline in infections has prompted political leaders to offer an array of incentives, such as free tickets to ballgames and lotteries, including New York State's $US5 million ($A6.5 million) "Vax & Scratch" game.
De Blasio on Monday upped the state's ante by adding weekly drawings of prizes, including Broadway shows, hotel packages and one-year gym memberships for residents who get vaccinated at city-run sites through early July.
He also announced that late-night comedian Stephen Colbert would resume taping The Late Show with Stephen Colbert in front of a live, vaccinated New York audience on June 14.
The US Food and Drug Administration this month approved the Pfizer coronavirus vaccine for children as young as 12 years old, and Moderna Inc said it planned to seek approval of its vaccine for children, as well.