Washington state Gov. Jay Inslee sent a letter to the White House Monday requesting staffing resources to help the state's overwhelmed hospitals.

"Once the Delta variant hit Washington state, COVID-19 hospitalizations skyrocketed. From mid-July to late August, we saw hospitalizations double about every two weeks," Inslee wrote. "The hospitals have surged to increase staffed beds and stretch staff and have canceled most non-urgent procedures, but are still over capacity across the state."

"While there are hopeful signs that the current wave of infection is peaking, and some states are beginning to see declines, we have not yet seen that effect here," the governor said.

Washington state had already asked for 1,200 federal government staffers and is now "requesting the deployment of Department of Defense medical personnel to assist with the current hospital crisis," Inslee said.

A second dose of Johnson & Johnson's COVID-19 vaccine given two months after the first leads to stronger protection, the company said Tuesday.

Compared to the Pfizer and Moderna vaccines, Johnson & Johnson's single-shot vaccine always had slightly lower efficacy. Peak efficacy from the two-shot Pfizer and Moderna vaccines was 95% and 94%, respectively, against symptomatic illness, compared to 72% with J&J's one shot. But two Johnson & Johnson shots, given two months apart, resulted in a similarly high effectiveness level: 94% protection against any symptomatic infection in the U.S. and 100% against severe disease.

J&J chief scientific officer Dr. Paul Stoffels said the single-shot vaccine still provides "strong and long-lasting protection" while also being "easy to use, distribute and administer."

"At the same time," Stoffels said, "we now have generated evidence that a booster shot further increases protection against COVID-19 and is expected to extend the duration of protection significantly."

-ABC News' Sony Salzman

The U.S. reported more than 225,000 child COVID-19 cases, marking the fourth consecutive week with over 200,000 new pediatric cases reported, according to a newly released weekly report from the American Academy of Pediatrics and the Children’s Hospital Association.

In the last five weeks alone, the country has reported more than 1.1 million pediatric cases, according to the organizations.

"The weekly figure is now about 26 times higher than it was in June, when just 8,400 pediatric cases were reported over the span of a week," the organizations wrote in their report.

The South accounted for about half --110,000-- of last week's pediatric cases, according to the report.

The organizations added that more than 2,200 children are hospitalized with a confirmed or suspected COVID-19 infection.

-ABC News' Arielle Mitropoulos

The U.S. surpassed 675,000 coronavirus deaths Monday, according to Johns Hopkins University's Coronavirus Resource Center.

The 675,446 deaths since the pandemic began in March of 2020 now surpasses the deaths from the 1918 pandemic.

Although the seven-day average of new deaths is nowhere near the 3,600 deaths recorded in mid-January, the average has been increasing since mid-July, according to the U.S. Centers for Disease Control and Prevention.

The seven-day average of new deaths has gone from 191 on July 10 to 1,353 on Sept. 19, the CDC data showed.

The majority of recent deaths has been among unvaccinated Americans, according to the data.

School districts without a universal masking policy in place at the start of the school year saw a significant increase in COVID-19 outbreaks, according to three new studies released by the Centers for Disease Control and Prevention.

Additionally, school districts in those counties saw more than double the number of pediatric COVID-19 cases during this same period, the studies, released Friday, also found.

The studies further emphasize that school mask requirements, along with other prevention strategies, are critical to reducing the spread of COVID-19 in schools.

Other key findings from the studies include:

- Schools in Arizona that opened without a school mask requirement had a 3.5 higher likelihood of having a COVID-19 outbreak than schools that opened with a school mask requirement.

-During the early part of the 2021-2022 academic school year, almost 2,000 schools have been closed and more than 900,000 students in more than 40 states have been impacted.

- Pediatric cases during the start of the 2021-2022 school year were about half in U.S. counties with school mask requirements than in counties without school mask requirements.

To prevent COVID-19 outbreaks in schools, the CDC recommends a multi-layered strategy including vaccination, universal indoor masking, testing and physical distancing.

-ABC News' Eric Strauss