The US is seeing a nationwide drop in students attending school as the Omicron variant surges, causing students and staff to stay out of classrooms. 

Most of the nation's nearly 100,000 public schools are open, but each day attendance gets lower for some schools as the Omicron takes its toll and anxious parents keep their children home to avoid the highly transmissible variant.

New York City's public school district, the nation's largest, saw overall attendance fall below 70 percent when classes resumed last week after the holidays, The Wall Street Journal reported on Wednesday. Before the pandemic, the average attendance in the school district was more than 90 percent. 

At one high school in Brooklyn, hundreds of students were sent to the auditorium after about 50 teachers called out sick, and the school couldn't find enough substitutes. 

At another school in the Bronx, 5 out of 100 senior students showed up in class. The school had to switch to "Zoom in a room" with students on devices in largely empty classrooms, Chalkbeat New York reported. 

"There's this idea that schools are open and learning is happening, but in every single one of those you're dealing with people who are sick," Jeremy Ehrlich, a teacher at the Bronx's New World High School, told Chalkbeat New York.

Far more students and staff have reported testing positive for the coronavirus since Dec 24 than the rest of the school year combined, health officials said. On Tuesday alone, nearly 7,500 students and 1,259 staff reported testing positive, according to the New York City Education Department.

In Boston, student attendance in public schools has hovered around 70 percent since the winter break ended Jan 4, down from about 90 percent before the holidays, the Journal reported. 

"The most that I've had in any of my classes was just two. It was me and another kid," Aaron Hernandez, a junior at Milpitas High School in California told CBS News. 

A shortage of COVID tests is also playing a part in the low attendance. The Centers for Disease Control and Prevention (CDC) says COVID-19 testing should be offered for students or teachers and staff at least once every week when community transmission happens.

The Biden administration on Wednesday promised to provide an additional 10 million COVID-19 tests per month to schools and students to keep classrooms open. That is on top of more than $10 billion for school-based tests authorized in the COVID-19 relief law and about $130 billion earmarked in that law to keep children in school.

According to a White House fact sheet, 5 million PCR tests and 5 million rapid tests will be distributed to schools. Those tests also may be used to create test-to-stay programs, for which students exposed to the coronavirus will be allowed to stay in the classrooms as long as they periodically test negative. The CDC endorsed that approach last month.

The new supply of tests is likely enough to cover only a small fraction of students, as about 53 million are attending K-12 public schools as of 2019, according to the US Census Bureau. 

Increasing the school test supply will likely be too late for many trying to safely navigate the Omicron surge, which is already showing signs of cresting, The Associated Press reported. 

In some large urban districts, schools are struggling to get their students tested. New York's schools announced last week that they were doubling participation in their regular surveillance testing. But union officials noted at the expanded level, the optional screenings covered only 20 percent of the district's students at most, The New York Times reported. 

Just over 17 percent of US children ages 5 to 11 were fully vaccinated as of Tuesday, more than two months after shots for the age group became available, health officials said.

Vaccinations among elementary school children surged after the shots were introduced in the fall, but the numbers have increased slowly, and Omicron's spread appears to have had little impact.

The low rates are "very disturbing", said Dr Robert Murphy, executive director for the Institute for Global Health at Northwestern University's Feinberg School of Medicine. Hospitalizations of children under 18 have climbed to their highest levels on record in the past few weeks.

In Tennessee, lawmakers have proposed a bill that would allow parents who disagree with COVID-19 protocols in their school districts to remove their children from the schools and be given a voucher to attend a different school, FOX13 Memphis reported. The vouchers would be available to students in districts where they were not offered 180 days in class due to the pandemic or where a mask mandate was imposed, the station reported.

The continuing pandemic is also taking its toll on recruitment by the US Army, which for the first time is offering a maximum enlistment bonus of $50,000 to highly skilled recruits who join for six years, The Associated Press reported Thursday. Until now, the Army has offered a maximum bonus of $40,000.

Major General Kevin Vereen, head of Army Recruiting Command, told AP that shuttered schools and the competitive job market over the past year have posed significant challenges for recruiters. 

Last year, the Army's recruiting goal was 57,500, and Vereen said it will be about the same this year.